Composite solid electrolyte with defect engineering induced heat-force synergistic effect and preparation method of composite solid electrolyte
By performing defect engineering on hexagonal boron nitride powder, an efficient thermal diffusion network and a fast lithium-ion transport channel were constructed, solving the problems of insufficient thermal management, mechanical strength and ion transport of solid polymer electrolytes, and realizing a high-performance composite solid electrolyte.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN UNIV
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-01
AI Technical Summary
Existing solid polymer electrolytes have low thermal conductivity, which easily leads to local hot spots. Their insufficient mechanical properties make it difficult to suppress lithium dendrites, and their low ionic conductivity and lithium-ion transference number affect battery performance and safety.
Defect engineering was used to process hexagonal boron nitride powder. Structural defects were introduced by oscillating ball milling and then combined with a polymer matrix and lithium salt to construct an efficient thermal diffusion network, form a stable solid electrolyte interface layer, and build a fast lithium-ion transport channel.
It achieves efficient thermal diffusion, mechanical enhancement, and rapid ion transport, significantly improving the electrolyte's thermal stability, dendrite suppression ability, and ionic conductivity, reaching a high ion transference number, and supporting long-cycle stability and high safety lithium metal batteries.
Smart Images
Figure CN121964798A_ABST
Abstract
Description
A composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect and its preparation method Technical Field
[0001] This invention relates to the field of solid-state lithium battery technology, and in particular to a composite solid electrolyte with a defect engineering-induced thermo-mechanical synergistic effect and its preparation method. Background Technology
[0002] With the rapid development of portable electronic devices and electric vehicles, higher demands are being placed on the energy density and safety performance of lithium batteries. Traditional lithium-ion batteries use graphite-based anode materials, which have a relatively low theoretical specific capacity (approximately 372 mAh g⁻¹). -1 This limits further improvements in battery energy density. Lithium metal anodes, due to their ultra-high theoretical specific capacity (3860 mAh g⁻¹), [are limited]. -1 With its low electrochemical potential (relative to the standard hydrogen electrode -3.04 V), lithium metal is considered an ideal choice for next-generation high-energy-density batteries. However, the high reactivity of lithium metal makes it poorly compatible with commercial liquid electrolytes, easily leading to uneven lithium deposition and dendrite growth, which exacerbates side reactions, reduces coulombic efficiency, and can even cause thermal runaway, seriously threatening battery safety. Therefore, the development of lithium metal solid-state electrolyte technology is of great strategic importance.
[0003] Solid polymer electrolytes (SPEs) have attracted widespread attention due to their advantages such as good flexibility and ease of processing, but they still have shortcomings: On the one hand, the low thermal conductivity of the polymer matrix makes it easy for local heat accumulation to form "hot spots" during charging and discharging, accelerating dendrite growth and ultimately causing battery failure; on the other hand, the limited mechanical strength of the electrolyte makes it difficult to suppress dendrite growth in the long term. In addition, the low ionic conductivity and lithium-ion transference number of the electrolyte lead to obstructed ion transport, affecting battery performance.
[0004] Composite solid electrolytes (CPEs) utilize the introduction of inorganic fillers as an effective strategy. Hexagonal boron nitride, as a two-dimensional inorganic material, possesses intrinsically high thermal conductivity (approximately 300 W / m²). - ¹ K - ¹) and high modulus, theoretically can simultaneously improve the thermal diffusivity and mechanical strength of the electrolyte. However, the traditional hexagonal boron nitride has a complete layer structure and inert surface, lacking lithium-ion transport active sites, which means that it is often used only as an inert filler in practical applications and cannot fully play its functional role.
[0005] Therefore, existing technologies need to be improved. Summary of the Invention
[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect and its preparation method, aiming to solve the problems of existing solid polymer electrolytes in terms of thermal management, dendrite suppression and ion transport.
[0007] The technical solution of the present invention is as follows: A method for preparing a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect includes the following steps: S1, placing raw hexagonal boron nitride powder and milling beads together in a ball mill jar, and then milling in a vibrating ball mill at a speed of 800~1200 RPM for 1~2 hours to obtain defective hexagonal boron nitride powder; S2, adding polyvinylidene fluoride (PVDF), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and the defective hexagonal boron nitride powder into a polar solvent, and then stirring and ultrasonicating to obtain a uniformly mixed slurry; S3, casting and drying the slurry to obtain a flexible and dense film, which is the composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect.
[0008] Optionally, in S1, during ball milling, pause for 5-10 minutes after each 10-15 minute milling session.
[0009] Optionally, in S1, the ball-to-particle ratio of the grinding beads to the hexagonal boron nitride powder is (30~40):1.
[0010] Optionally, the polar solvent is N-methylpyrrolidone (NMP) or N,N-dimethylformamide (DMF).
[0011] Optionally, the mass ratio of polyvinylidene fluoride (PVDF) to lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is (3~5):2, and the defective hexagonal boron nitride powder accounts for 5-10% of the mass of PVDF.
[0012] Optionally, the stirring in S2 is performed by magnetic stirring at 60~80°C for 6~12 hours.
[0013] Optionally, the ultrasonic power in S2 is 180W~360W and the duration is 15~30 minutes.
[0014] Optionally, S3 specifically includes: casting the slurry onto a polytetrafluoroethylene (PTFE) mold, and then drying it in a vacuum drying oven at 60~80°C for 12~16 hours or more.
[0015] Secondly, the present invention provides a composite solid electrolyte with a defect engineering-induced thermo-mechanical synergistic effect, prepared by the aforementioned preparation method, or comprising polyvinylidene fluoride (PVDF), lithium bis(trifluoromethanesulfonylimide) (LiTFSI), and defective hexagonal boron nitride powder, wherein the defective hexagonal boron nitride powder is prepared by the following method: the original hexagonal boron nitride powder and the grinding beads are placed together in a grinding jar, and then the mixture is ball-milled in a vibrating ball mill at a speed of 800~1200 RPM for 1~2 hours.
[0016] Beneficial Effects: This invention provides a composite solid electrolyte with a defect-engineered thermo-mechanical synergistic effect and its preparation method. This invention employs a pendulum ball milling method (i.e., high-speed vibratory ball milling) to perform defect engineering on raw hexagonal boron nitride powder, transforming it from an inert filler into a multifunctional filler with a "thermo-mechanical synergistic effect." Then, this defective hexagonal boron nitride powder is composited with a polymer matrix and lithium salt, and a composite electrolyte membrane is prepared by solution casting. In terms of thermal management, the hexagonal boron nitride powder of this invention acts as a framework in the PVDF matrix to construct an efficient thermal diffusion network, homogenize the interface temperature field, eliminate local hot spots, and inhibit lithium dendrite growth. In terms of mechanical enhancement, the active sites exposed by defects not only promote LiTFSI dissociation but also induce the formation of a stable solid electrolyte interface layer rich in high-modulus components such as lithium fluoride and lithium nitride, mechanically inhibiting dendrite growth. Simultaneously, in terms of ion transport, the defect sites construct unique fast lithium-ion transport channels, significantly improving ionic conductivity and lithium-ion transference number. The composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect obtained by this invention achieves a high ion transference number of 0.65, maintains polarization stability for more than 1200 hours, can undergo 500 long cycles with a capacity retention rate of up to 85%, and has a thermal conductivity between 1.4 and 4.7. Attached Figure Description
[0017] Figure 1 is a schematic diagram of the process for preparing the composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect according to the present invention.
[0018] Figure 2 shows the XRD comparison diagram of hexagonal boron nitride powder.
[0019] Figure 3 shows a TEM comparison image of hexagonal boron nitride powder.
[0020] Figure 4 is a COMSOL simulation diagram of the phase field of the lithium metal anode and the electrolyte layer obtained in Example 1 and Comparative Example 1.
[0021] Figure 5 is a COMSOL simulation diagram of the temperature field of the lithium metal anode and the electrolyte layer obtained in Example 1 and Comparative Example 1.
[0022] Figure 6 shows the ionic conductivity of the composite solid electrolyte obtained in Example 1.
[0023] Figure 7 shows the lithium-ion transfer rate of the composite solid electrolyte obtained in Example 1.
[0024] Figure 8 shows the polarization diagram of the lithium symmetric battery with the composite solid electrolyte obtained in Example 1.
[0025] Figure 9 shows the long-cycle diagram of the LiFePO4 / Li battery with the composite solid electrolyte obtained in Example 1.
[0026] Figure 10 shows the thermal conductivity of composite solid electrolytes with different contents of defective hexagonal boron nitride powder. Detailed Implementation
[0027] This invention provides a composite solid electrolyte exhibiting a defect engineering-induced thermo-mechanical synergistic effect and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0028] Existing solid polymer electrolytes have low thermal conductivity, which easily leads to local hot spots and thermal runaway; they also have insufficient mechanical properties, making it difficult to suppress lithium dendrites, and have low ionic conductivity and lithium ion transference number.
[0029] Composite solid-state electrolytes (CPEs) have become an effective strategy for addressing the limited mechanical strength of electrolytes and the difficulty in suppressing dendrite growth over long periods by introducing inorganic fillers. Currently available hexagonal boron nitride, as a two-dimensional inorganic material, possesses intrinsically high thermal conductivity (approximately 300 W / m²). - ¹ K - ¹) and high modulus, theoretically can simultaneously improve the thermal diffusivity and mechanical strength of the electrolyte. However, the traditional hexagonal boron nitride has a complete layer structure and inert surface, lacking lithium-ion transport active sites, which means that it is often used only as an inert filler in practical applications and cannot fully play its functional role.
[0030] To address the aforementioned bottlenecks, defect engineering, as an effective material modification strategy, allows inventors to intentionally introduce structural defects to control materials, providing a new approach for the development of multifunctional boron nitride fillers.
[0031] Based on this, this embodiment provides a method for preparing a composite solid electrolyte, as shown in Figure 1, including the following steps: S1, placing the original hexagonal boron nitride powder and milling beads together in a ball mill jar, and then milling in a vibrating ball mill at a speed of 800~1200 RPM for 1~2 hours to obtain defective hexagonal boron nitride powder; S2, adding polyvinylidene fluoride (PVDF), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and the defective hexagonal boron nitride powder into a polar solvent, and then stirring and sonicating to obtain a uniformly mixed slurry; S3, casting and drying the slurry to obtain a flexible and dense film, which is the composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect.
[0032] It should be noted that this invention functionally modifies traditional inert hexagonal boron nitride powder through defect engineering, transforming it from a single physical reinforcing filler into a multifunctional active component with a "thermo-mechanical synergistic effect." Defects are generated in the hexagonal boron nitride using mechanical ball milling, and then it is composited with a polymer matrix and lithium salt. A composite electrolyte membrane is prepared using a solution casting method. In the composite solid electrolyte of this invention, defects play three key roles: First, they utilize a two-dimensional boron nitride framework to construct an efficient thermal diffusion network, homogenizing the interface temperature field and fundamentally eliminating "local hot spots," achieving thermal stability. Second, the exposed defective active sites promote the dissociation of lithium salt (lithium bis(trifluoromethanesulfonylimide)) and induce a reaction with the lithium metal anode, forming a stable solid electrolyte interface layer rich in high-modulus components such as lithium fluoride and lithium nitride, thereby mechanically suppressing dendrites and stabilizing interface chemistry. Third, the defect sites construct unique fast lithium-ion transport channels, effectively improving ionic conductivity and lithium-ion transference number. This is achieved through the integrated design of the aforementioned "thermo-mechanical synergistic effect" and enhanced ion transport. This embodiment successfully solves the multiple interface challenges in solid-state lithium metal batteries. The electrolyte exhibits significantly improved overall performance, including high ionic conductivity, high lithium-ion transference number, excellent thermal stability and cycle stability, and can effectively suppress lithium dendrite growth, providing a key material foundation for realizing high-safety, long-life all-solid-state lithium metal batteries. Finally, this invention deeply analyzes the ion conduction mechanism in the defect-engineered boron nitride-induced thermo-mechanical synergistic effect composite polymer solid-state electrolyte through model construction, testing and analysis, and data calculation, and derives the structural theory of the thermo-mechanical synergistic effect composite solid-state electrolyte.
[0033] In some implementations, during S1, the ball milling process is paused for 5-10 minutes after every 10-15 minutes of milling. This intermittent operation mode not only effectively controls the local temperature, ensuring the stability and repeatability of the defective structure, but also cools the machine and protects it.
[0034] In one embodiment, in S1, the ball-to-particle ratio of the grinding beads to the hexagonal boron nitride powder is (30~40):1.
[0035] It should be noted that a ball-to-powder ratio that is too low, such as 20:1, will result in insufficient grinding energy, low collision efficiency, and difficulty in effectively introducing defects during ball milling. A ball-to-powder ratio that is too high, such as 50:1, will increase costs by using too many grinding balls, with little performance benefit.
[0036] In one embodiment, the polar solvent is N-methylpyrrolidone (NMP) or N,N-dimethylformamide (DMF).
[0037] In some embodiments, the mass ratio of polyvinylidene fluoride (PVDF) to lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is (3~5):2, and the defective hexagonal boron nitride powder accounts for 5-10% of the mass of PVDF.
[0038] It should be noted that if the LiTFSI content in the composite solid electrolyte is too high, such as a PVDF:LiTFSI mass ratio of 1:1, it will result in a low polymer content, which will affect the formation of the electrolyte membrane (affecting film-forming properties, such as causing pores or preventing the formation of a solid electrolyte); if the LiTFSI content is even lower, such as a PVDF:LiTFSI mass ratio of 6:2, it will result in a decrease in ionic conductivity, which will affect performance.
[0039] In the ratio of defective hexagonal boron nitride (d-BN) to PVDF, if d-BN is too little, such as 1%, it will lead to insufficient thermal performance and fail to achieve the thermo-synergistic effect, thus affecting the electrolyte performance (too little will have no effect); if d-BN is too much, such as more than 20%, the filler will agglomerate and decrease, thus affecting the performance.
[0040] In some embodiments, the stirring in S2 is performed by magnetic stirring at 60-80°C for 6-12 hours.
[0041] In some implementations, the ultrasonic power in S2 is 180W~360° and the duration is 15~30 minutes.
[0042] Insufficient ultrasonic power or too short a duration will lead to uneven dispersion of d-BN, causing agglomeration and affecting performance. Excessive power or too long a duration will not significantly improve performance and result in insufficient benefits.
[0043] In some embodiments, S3 specifically includes: casting the slurry onto a polytetrafluoroethylene (PTFE) mold, and then drying it in a vacuum drying oven at 60~80°C for 12~16 hours or more.
[0044] The composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect provided in this embodiment is prepared by the preparation method described above, or includes polyvinylidene fluoride (PVDF), lithium bis(trifluoromethanesulfonylimide) (LiTFSI), and defective hexagonal boron nitride powder. The defective hexagonal boron nitride powder is prepared by the following method: the original hexagonal boron nitride powder and the grinding beads are placed together in a grinding jar, and then ball-milled in a vibrating ball mill at a speed of 800~1200 RPM for 1-2 hours.
[0045] This embodiment prepares a composite solid electrolyte by mixing defective hexagonal boron nitride powder with polyvinylidene fluoride (PVDF) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). This electrolyte can simultaneously achieve efficient thermal diffusion, mechanically enhanced dendrite suppression, and rapid ion transport, thereby constructing a stable lithium metal battery interface.
[0046] The present invention will be further described below through specific embodiments.
[0047] Example 1: A method for preparing a composite solid electrolyte with a defect engineering-induced thermo-mechanical synergistic effect, comprising the following steps: raw hexagonal boron nitride powder with a ball-to-material ratio of 40:1 is placed together with grinding beads in a ball mill jar, and then ball-milled in a vibrating ball mill at a speed of 1200 RPM for 1 hour to obtain defective hexagonal boron nitride powder. To ensure that the equipment does not overheat and to maintain the stability of the process, an intermittent operation mode is adopted, with a 5-minute pause every 10 minutes of operation for machine cooling.
[0048] Polyvinylidene fluoride (PVDF), lithium bis(trifluoromethanesulfonylimide) (LiTFSI), and the defective hexagonal boron nitride powder were added to N-methylpyrrolidone (NMP), and then stirred and ultrasonicated to obtain a uniformly mixed slurry. In this embodiment, the mass ratio of PVDF to LiTFSI is 3:2, and the defective hexagonal boron nitride powder accounts for 5% of the mass of PVDF.
[0049] The above solution was magnetically stirred at 60°C for 6 hours until PVDF and LiTFSI were completely dissolved, resulting in a mixed slurry. The slurry was then ultrasonically treated for 30 minutes to ensure that the defective hexagonal boron nitride was fully and uniformly dispersed in the polymer solution system, preventing agglomeration and thus forming a continuous functional network in the composite solid electrolyte. The uniformly mixed slurry was poured onto a flat polytetrafluoroethylene (PTFE) mold, and then the entire mold was transferred to a vacuum drying oven at 80°C for 12 hours to completely remove the NMP solvent, ultimately yielding a flexible and dense composite solid electrolyte membrane, which is the composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect.
[0050] The difference between Example 2 and Example 1 is that in this example, the mass ratio of PVDF to LiTFSI is 3:2, and the defective hexagonal boron nitride powder accounts for 8% of the mass of PVDF.
[0051] The difference between Example 3 and Example 1 is that in this example, the mass ratio of PVDF to LiTFSI is 3:2, and the defective hexagonal boron nitride powder accounts for 10% of the mass of PVDF.
[0052] The difference between Comparative Example 1 and Example 1 is that the hexagonal boron nitride powder used in the composite solid electrolyte prepared in this comparative example is the original hexagonal boron nitride powder, that is, hexagonal boron nitride powder that has not undergone defect engineering treatment.
[0053] The difference between Comparative Example 2 and Example 1 is that the mass ratio of PVDF to LiTFSI in this comparative example is 3:2, and the defective hexagonal boron nitride powder accounts for 15% of the mass of PVDF.
[0054] The difference between Comparative Example 3 and Example 1 is that the mass ratio of PVDF to LiTFSI in this comparative example is 3:2, and the defective hexagonal boron nitride powder accounts for 2% of the mass of PVDF.
[0055] The difference between Comparative Example 4 and Example 1 is that the steps for preparing defective hexagonal boron nitride powder in this comparative example are as follows: Raw hexagonal boron nitride powder with a ball-to-powder ratio of 40:1 is placed together with grinding beads in a ball milling jar, and then milled in a conventional planetary ball mill at 1200 RPM for 5 hours to obtain defective hexagonal boron nitride powder. To ensure that the equipment does not overheat and to maintain the stability of the process, an intermittent operation mode is adopted, for example, pausing for 5 minutes every 10 minutes of operation for machine cooling.
[0056] The defective hexagonal boron nitride powders obtained in the above examples and comparative examples were analyzed. Figure 2 shows the XRD comparison of the hexagonal boron nitride powders. From top to bottom, the figures show the XRD patterns of the original hexagonal boron nitride powder, the defective hexagonal boron nitride powder obtained in Comparative Example 4, and the defective hexagonal boron nitride powder obtained in Example 1. Figure 3 shows the TEM comparison of the hexagonal boron nitride powders. In Figure 3, the left image is the TEM image of the defective hexagonal boron nitride powder obtained in Example 1, and the right image is the TEM image of the defective hexagonal boron nitride powder obtained in Comparative Example 4. As shown in Figure 2, the comparative sample using planetary ball milling still maintains obvious hexagonal boron nitride characteristic diffraction peaks, while the hexagonal boron nitride characteristic diffraction peaks of this embodiment have basically disappeared, exhibiting typical amorphous characteristics. As shown in Figure 3, the comparative sample using planetary ball milling exhibits a complete crystal lattice morphology, proving that planetary ball milling cannot generate defects in a short time, while the crystal lattice of the sample prepared by the method of this invention is severely damaged. This fully demonstrates that the sample prepared by the method of this invention has a higher defect density and a more significant amorphous structure, laying an important structural foundation for realizing the "thermo-mechanical synergistic effect" in composite solid electrolytes.
[0057] We established a multiphysics coupling model using COMSOL Multiphysics software to simulate and analyze the thermal management capability and dendrite suppression mechanism of the electrolyte. In our simulation, a battery model containing a lithium metal anode and an electrolyte layer was established. A phase-field model describing dendrite growth was constructed through the general form partial differential equation interface of the mathematical module. Three general form partial differential equations were set to describe the dendrite evolution process. By adjusting the anisotropy intensity, symmetry factor, and electrochemical reaction rate parameters, dendrite growth behavior under different conditions was simulated. Simultaneously, the solid-state heat transfer physics field of the heat transfer module was used, with corresponding temperature boundary conditions and heat source terms set to simulate the thermal behavior during battery charging and discharging. As shown in Figures 4 and 5, the simulation results demonstrate that the composite electrolyte containing defect-engineered boron nitride from Example 1 exhibits excellent thermal management performance. The maximum temperature gradient in the traditional polymer electrolyte reaches 10 K, while the temperature gradient in the composite electrolyte is only 4.9 K, effectively eliminating local hot spots. This result verifies the homogenizing effect of the three-dimensional thermal diffusion network constructed by defective hexagonal boron nitride on the interface temperature field. Regarding dendrite suppression, phase-field simulations show that the maximum dendrite length in polymer electrolytes is reduced by 62% compared to pure polymer electrolytes, and the dendrite morphology is more passivated. Simulation results validate the structural theory of defect-engineered thermo-mechanical synergistic effects in composite solid electrolytes.
[0058] Figure 6 shows the ionic conductivity of the composite solid electrolyte obtained in Example 1. Figure 7 shows the lithium-ion transference number of the composite solid electrolyte obtained in Example 1. As can be seen from Figures 6 and 7, the composite solid electrolyte of Example 1 has high ionic conductivity and high ion transference number.
[0059] Figure 8 shows the polarization diagram of the lithium symmetric battery with the composite solid electrolyte obtained in Example 1. As can be seen from Figure 8, the lithium symmetric battery using the composite solid electrolyte of this example can maintain polarization stability for over 1200 hours. The composite solid electrolyte obtained in Example 1 was assembled into a coin cell to test its long-cycle capability. The results are shown in Figure 9. The battery can undergo 500 cycles at a certain rate current with a capacity retention of up to 85%. Therefore, the strategy of inducing thermo-mechanical synergy through defect engineering in this invention provides a breakthrough solution for constructing high-safety, long-life solid lithium metal batteries.
[0060] The thermal conductivity of the composite electrolytes obtained in Examples 1-3 and Comparative Examples 2 and 3 was measured, and the resulting structures are shown in Figure 10. As can be seen from the figure, the values from left to right are 1.421, 2.951, 4.664, 4.566, 4.236, and 2.625, respectively. Good thermal conductivity is only achieved when the content is between 5-10%. Outside this range, such as at 2%, insufficient thermal performance is observed, failing to achieve the thermo-mechanical synergy effect and thus affecting electrolyte performance (too little content has no effect). Lower thermal conductivity cannot eliminate localized hot spots on the surface, preventing the achievement of the thermo-mechanical synergy effect. If too much d-BN is present, such as above 15%, the thermal conductivity decreases significantly.
[0061] In summary, this invention provides a composite solid electrolyte with a defect-engineered thermo-mechanical synergistic effect and its preparation method. This invention employs a pendulum ball milling method (i.e., high-speed vibratory ball milling) to perform defect engineering on raw hexagonal boron nitride powder, transforming it from an inert filler into a multifunctional filler with a "thermo-mechanical synergistic effect." This defective material is then composited with a polymer matrix and lithium salt, and a composite electrolyte membrane is prepared using a solution casting method. In terms of thermal management, the hexagonal boron nitride powder of this invention acts as a framework in the PVDF matrix, constructing an efficient thermal diffusion network, homogenizing the interface temperature field, eliminating local hot spots, and inhibiting lithium dendrite growth. In terms of mechanical enhancement, the active sites exposed by the defects not only promote LiTFSI dissociation but also induce the formation of a stable solid electrolyte interface layer rich in high-modulus components such as lithium fluoride and lithium nitride, mechanically inhibiting dendrite growth. Simultaneously, in terms of ion transport, the defect sites construct unique fast lithium-ion transport channels, significantly improving ionic conductivity and lithium-ion transference number.
[0062] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A method for preparing a composite solid electrolyte with a defect engineering-induced thermo-mechanical synergistic effect, characterized in that, The process includes the following steps: S1, placing the original hexagonal boron nitride powder and milling beads together in a ball mill jar, and then milling in a vibrating ball mill at a speed of 800~1200 RPM for 1~2 hours to obtain defective hexagonal boron nitride powder; S2, adding polyvinylidene fluoride, lithium bis(trifluoromethanesulfonyl)imide and the defective hexagonal boron nitride powder into a polar solvent, and then stirring and ultrasonicating to obtain a uniformly mixed slurry; S3, casting and drying the slurry to obtain a flexible and dense film, which is the composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect.
2. The method for preparing a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect according to claim 1, characterized in that, In S1, during ball grinding, pause for 5-10 minutes after each 10-15 minute grinding session.
3. The method for preparing a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect according to claim 1, characterized in that, In S1, the ball-to-particle ratio of the grinding beads to the hexagonal boron nitride powder is (30~40):
1.
4. The method for preparing a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect according to claim 1, characterized in that, The polar solvent is N-methylpyrrolidone or N,N-dimethylformamide.
5. The method for preparing a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect according to claim 1, characterized in that, The mass ratio of polyvinylidene fluoride to lithium bis(trifluoromethanesulfonylimide) is (3~5):2, and the defective hexagonal boron nitride powder accounts for 5-10% of the mass of polyvinylidene fluoride.
6. The method for preparing a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect according to claim 1, characterized in that, The stirring in S2 is performed by magnetic stirring at 40~60℃ for 6~12 hours.
7. The method for preparing a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect according to claim 1, characterized in that, The ultrasonic power in S2 is 180~360W and the duration is 15~30 minutes.
8. The method for preparing a composite solid electrolyte with defect engineering-induced thermo-mechanical synergistic effect according to claim 1, characterized in that, S3 specifically includes: pouring the slurry onto a mold, and then drying it in a vacuum drying oven at 60~80℃ for 12~16 hours.
9. A composite solid electrolyte exhibiting a defect engineering-induced thermo-mechanical synergistic effect, characterized in that, Prepared by the preparation method according to any one of claims 1-8, or comprising polyvinylidene fluoride, lithium bis(trifluoromethanesulfonylimide) and defective hexagonal boron nitride powder, wherein the defective hexagonal boron nitride powder is prepared by the following method: the original hexagonal boron nitride powder and the grinding beads are placed together in a grinding jar, and then ball-milled in a vibrating ball mill at a speed of 800-1200 RPM for 1-2 hours.