A modified lithium metal anode material and its preparation method, a composite modified lithium metal anode material and its preparation method, and a battery.

Abstract

This invention belongs to the field of lithium-ion battery materials, and discloses a modified lithium metal anode material and its preparation method, a composite modified lithium metal anode material and its preparation method, and a battery. The modified lithium metal anode material includes a lithium metal sheet and an organic polymer layer. The organic polymer layer is disposed on any surface of the lithium metal sheet. Multiple through-holes are formed on the lithium metal sheet, and these through-holes are uniformly spaced and filled with organic polymer. Applying the modified lithium metal anode material to a battery can effectively suppress the formation of lithium dendrites and improve the battery's cycle stability and gravimetric energy density.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery materials and relates to an anode material, specifically a modified lithium metal anode material and its preparation method and application. Background Technology

[0002] Lithium metal anodes offer advantages such as high specific capacity and high operating voltage, contributing to improved energy density and charging speed in lithium batteries. The theoretical specific capacity of lithium metal anodes reaches 3860 mAh / g, more than 10 times that of traditional graphite anodes (372 mAh / g). This means that, within the same volume, lithium metal anodes can store more charge, thus extending battery life. The high operating voltage of lithium metal anodes reduces battery internal resistance, thereby increasing charging speed and significantly shortening charging time for devices such as electric vehicles. However, during charge-discharge cycles, lithium metal anodes are prone to lithium dendrite formation, which can potentially puncture the separator, leading to battery short circuits and safety hazards. Summary of the Invention

[0003] In view of the defects and deficiencies of the existing technology, the present invention provides, in a first aspect, a modified lithium metal anode material; in a second aspect, a method for preparing the modified lithium metal anode material; in a third aspect, a composite modified lithium metal anode material; in a fourth aspect, a method for preparing the composite modified lithium metal anode material; and in a fifth aspect, a battery.

[0004] In a first aspect, the present invention provides a modified lithium metal anode material, comprising a lithium metal sheet and an organic polymer layer, wherein the organic polymer layer is disposed on any surface of the lithium metal sheet, and a plurality of through holes are formed on the lithium metal sheet, the plurality of through holes being evenly spaced and filled with organic polymer.

[0005] Preferably, the through hole is any one or more of the following: a round hole, a polygonal hole, or a plum blossom-shaped hole.

[0006] Further preferably, the through hole is shaped like a plum blossom.

[0007] Preferably, the distance between the center point of the through hole and the circumscribed circle of the through hole is 3~6mm.

[0008] Preferably, the distance between the outer circles of two adjacent through holes is 1~10mm.

[0009] Preferably, the organic polymer is any one or more of PEO, PMMA, and PVDF-HFP.

[0010] Preferably, the thickness of the lithium metal sheet is 0.5~3mm; and the thickness of the organic polymer layer is 30~100μm.

[0011] Secondly, the present invention provides a method for preparing the above-mentioned modified lithium metal anode material, comprising: drilling holes in a lithium metal sheet under an inert atmosphere, then filling the holes with an organic polymer and coating it on the surface of the lithium metal sheet, and then curing it.

[0012] Preferably, the preparation method of the above-mentioned modified lithium metal anode material is as follows: drilling holes in a lithium metal sheet under an inert atmosphere, then coating an organic polymer onto the lithium metal sheet to fill the through holes of the lithium metal sheet and form an organic polymer layer on the surface of the lithium metal sheet, and then curing to obtain the modified lithium metal anode material.

[0013] Preferably, the curing method is to irradiate the lithium metal sheet under ultraviolet light for 5-10 seconds.

[0014] Thirdly, the present invention provides a composite modified lithium metal anode material, comprising the above-mentioned modified lithium metal anode material and a lithium-based electrolyte layer, wherein the lithium-based electrolyte layer is disposed on the surface of the organic polymer layer.

[0015] Preferably, the lithium-based electrolyte used in the lithium-based electrolyte layer is any one or more of LiTFSI, LiFSI, and LiBF4.

[0016] Preferably, the thickness of the lithium-based electrolyte layer is 10~50μm.

[0017] Fourthly, the present invention provides a method for preparing the above-mentioned composite modified lithium metal anode material, comprising: mixing a lithium-based electrolyte and a solvent to obtain a slurry, coating the slurry onto the surface of the organic polymer layer of the above-mentioned composite modified lithium metal anode material, and vacuum drying to obtain the composite modified lithium metal anode material.

[0018] Preferably, the solvent is any one or more of tetrahydrofuran, ethyl formate, ethyl acetate, and dimethyl carbonate.

[0019] Preferably, the solid-liquid ratio of the slurry is 1g:20~40mL.

[0020] Preferably, the vacuum drying temperature is 70~90℃ and the time is 4~12h.

[0021] Fifthly, the present invention provides a battery comprising the above-described modified lithium metal anode material or the above-described composite modified lithium metal anode material.

[0022] Compared with the prior art, one or more technical solutions provided by the present invention have at least one of the following beneficial effects:

[0023] (1) By creating through-holes in the lithium metal sheet, firstly, when lithium ions are deposited on the lithium metal sheet during charging and discharging, the energy at the open holes is higher than that at the flat areas. The deposition reaction shows a trend of decreasing energy, and lithium ions preferentially deposit at the through-holes, which can effectively suppress the formation of lithium dendrites and improve the cycle stability of lithium metal. Secondly, the porous lithium metal sheet can also reduce the weight of the negative electrode side and improve the mass energy density of the battery. Thirdly, the through-holes in the lithium negative electrode sheet can serve as liquid retention holes. Through the liquid storage and retention functions brought by the micropore and concave hole structure, the ion conduction efficiency, cycle stability and safety of the lithium-ion battery can be guaranteed.

[0024] (2) A lithium-based electrolyte layer is coated on the surface of the modified lithium metal anode material, which reduces the exposure time and area of ​​lithium metal in the air and reduces the possibility of side reactions. Furthermore, the lithium-based electrolyte layer can form a transition layer on the lithium metal surface, reducing the possibility of lithium dendrites piercing the battery separator. Attached Figure Description

[0025] Figure 1 Cycle curves of batteries assembled from the negative electrode materials obtained in Examples 1-5 and Comparative Examples 1-2;

[0026] Figure 2 This is a schematic diagram of the charging curve of a battery assembled from the negative electrode material prepared in Example 1.

[0027] Figure 3 A schematic diagram of the charging curve of a battery assembled from the negative electrode material prepared in Comparative Example 1.

[0028] Figure 4 This is a schematic diagram of the charging curve of a battery assembled from the negative electrode material prepared in Comparative Example 2. Detailed Implementation

[0029] The present invention provides the following specific technical solutions.

[0030] In a first aspect, the present invention provides a modified lithium metal anode material, comprising a lithium metal sheet and an organic polymer layer, wherein the organic polymer layer is disposed on any surface of the lithium metal sheet, and a plurality of through holes are formed on the lithium metal sheet, the plurality of through holes being evenly spaced and filled with organic polymer.

[0031] The inventors discovered that creating through-holes in lithium metal sheets has several advantages. First, during charging and discharging, lithium ions deposit on the lithium metal sheet at porous locations because they possess higher energy than on flat areas. Since the deposition reaction, similar to other reactions, exhibits a decrease in system energy, ions preferentially deposit at the through-hole locations. This effectively suppresses lithium dendrite formation, improves the cycle stability of lithium metal, and reduces the risk of battery short circuits and safety hazards. Second, porous lithium metal sheets can reduce the weight of the negative electrode side, increasing the battery's mass energy density. Third, the through-holes in the lithium negative electrode sheet can act as liquid retention pores. Due to capillary effects and the thickness of the film itself, the organic electrolyte in the pores forms concave or micropores. These micropores and concave structures provide liquid storage and retention functions, thus ensuring the ion conduction efficiency, cycle stability, and safety of the lithium-ion battery.

[0032] By filling the through-holes with organic polymer and setting an organic polymer layer, the organic polymer filling can alleviate the excessive accumulation of lithium dendrites at the hole cut-out points, ensuring that lithium preferentially deposits at the pores, but at the same time, it will not cause excessive lithium dendrite deposition.

[0033] Preferably, the through hole is any one or more of the following: a round hole, a polygonal hole, or a plum blossom-shaped hole.

[0034] In practical applications, polygonal holes are holes in the shapes of triangles, quadrilaterals (rectangles and squares), pentagons, etc.

[0035] Further preferably, the through hole is shaped like a plum blossom.

[0036] Through research, the inventors discovered that the plum blossom-shaped aperture has more folds but smoother edges, with almost no sharp corners. This shape maximizes lithium deposition, making lithium ion transport fast and efficient. Furthermore, the plum blossom-shaped aperture is less prone to the formation of dendrites in specific directions, resulting in a more stable structure. In contrast, while round apertures have no sharp corners, their lithium deposition capacity is relatively poor. Round apertures have more space for dendrite formation later on, making it easier for larger lithium dendrites to form and penetrate the film.

[0037] Through research, the inventors discovered that when the aperture of the through-hole is within the above-mentioned preferred range, the capillary effect can be reduced, thereby reducing the possibility of incomplete filling of the organic electrolyte, while ensuring the advantage of enhanced local surface potential energy and guaranteeing the modification effect.

[0038] Preferably, the distance between the center point of the through hole and the circumscribed circle of the through hole is 3~6mm.

[0039] Preferably, the distance between the outer circles of two adjacent through holes is 1~10mm.

[0040] Through research, the inventors discovered that ensuring a certain distance between the through holes improves the local surface potential energy of the lithium sheet through holes, resulting in better suppression of lithium dendrites and improved mechanical properties of the lithium metal sheet.

[0041] Preferably, the organic polymer is any one or more of PEO, PMMA, and PVDF-HFP.

[0042] Preferably, the thickness of the lithium metal sheet is 0.5~3mm; and the thickness of the organic polymer layer is 30~100μm.

[0043] The inventors discovered through research that the thickness of the lithium metal sheet is optimal for use in existing battery devices. If the lithium metal sheet is too thin, the content of active material will be significantly reduced, affecting the battery's long-cycle life. If the thickness is too high, a large number of lithium ions will not be able to participate in the reaction effectively, resulting in resource waste. Furthermore, excessive unreacted lithium may lead to safety issues such as battery bulging. A moderate thickness of the organic polymer layer reduces its impact on lithium-ion conduction, ensuring optimal composite performance.

[0044] Secondly, the present invention provides a method for preparing the above-mentioned modified lithium metal anode material, comprising: drilling holes in a lithium metal sheet under an inert atmosphere, then filling the holes with an organic polymer and coating it on the surface of the lithium metal sheet, and then curing it.

[0045] The preparation method of the above-mentioned modified lithium metal anode material is as follows: a lithium metal sheet is perforated under an inert atmosphere, and then an organic polymer is coated on the lithium metal sheet to fill the through holes of the lithium metal sheet and form an organic polymer layer on the surface of the lithium metal sheet. After curing, the modified lithium metal anode material is obtained.

[0046] Preferably, the curing method is to irradiate the lithium metal sheet under ultraviolet light for 5-10 seconds.

[0047] Thirdly, the present invention provides a composite modified lithium metal anode material, comprising the above-mentioned modified lithium metal anode material and a lithium-based electrolyte layer, wherein the lithium-based electrolyte layer is at least partially overlapped with the surface of the organic polymer layer in the modified lithium metal anode material.

[0048] Through research, the inventors discovered that coating the surface of the modified lithium metal anode material with a lithium-based electrolyte layer reduces the exposure time and area of ​​lithium metal in the air, thereby reducing the possibility of side reactions. Furthermore, the lithium-based electrolyte layer can form a transition layer on the lithium metal surface, reducing the possibility of lithium dendrites piercing the battery separator and further improving the battery's safety performance.

[0049] Preferably, the lithium-based electrolyte used in the lithium-based electrolyte layer is any one or more of LiTFSI, LiFSI, and LiBF4.

[0050] Preferably, the thickness of the lithium-based electrolyte layer is 10~50μm.

[0051] The inventors discovered through research that a lithium-based electrolyte layer can promote the rapid transport of lithium ions. An appropriate thickness of the lithium-based electrolyte layer reduces the impact on the specific capacity per unit volume of the battery, ensuring the lithium-ion transport rate and improving the battery's ion conductivity.

[0052] Fourthly, the present invention provides a method for preparing the above-mentioned composite modified lithium metal anode material, comprising: mixing a lithium-based electrolyte and a solvent to obtain a slurry, coating the slurry onto the surface of the organic polymer layer of the above-mentioned composite modified lithium metal anode material, and vacuum drying to obtain the composite modified lithium metal anode material.

[0053] Preferably, the solvent is any one or more of tetrahydrofuran, ethyl formate, ethyl acetate, and dimethyl carbonate.

[0054] Preferably, the solid-liquid ratio of the slurry is 1g:20~40mL.

[0055] Preferably, the vacuum drying temperature is 70~90℃ and the time is 4~12h.

[0056] Fifthly, the present invention provides a battery comprising the above-described modified lithium metal anode material or the above-described composite modified lithium metal anode material.

[0057] To make the technical problems, technical solutions and technical advantages of the present invention clearer, a detailed description will be given below with reference to specific examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0058] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0059] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0060] Example 1:

[0061] A method for preparing a composite modified lithium metal anode material includes the following steps:

[0062] Step 1: Under an argon atmosphere, use a quincunx-shaped punch to drill holes with a thickness of 2 mm and an area of ​​10 × 10 cm. 2The lithium metal sheet is perforated, with the distance from the center point of the through hole to the end of the petal being 4mm, and the distance between the outer tangent circles of two adjacent through holes being 2mm.

[0063] Step 2: PEO is uniformly dispersed on the porous lithium metal sheet prepared in step 1, and after filling multiple through holes, it is uniformly coated on the upper surface of the lithium metal sheet. Then, it is irradiated under ultraviolet light for 6 seconds to obtain the modified lithium metal anode material. The thickness of the PEO layer is 50 μm.

[0064] Step 3: LiTFSI is dropped into ethyl formate and continuously ground to disperse it evenly, resulting in a slurry with a liquid-to-solid ratio of 30 mL / g. The slurry is then uniformly coated onto the PEO layer of the modified lithium metal anode material obtained in Step 2, and then vacuum dried at 80°C for 6 hours. The resulting sheet material is the composite modified lithium metal anode material, wherein the thickness of the LiTFSI layer is 30 μm.

[0065] Example 2:

[0066] A method for preparing a composite modified lithium metal anode material includes the following steps:

[0067] Step 1: Under an argon atmosphere, use a quincunx-shaped punch to drill holes with a thickness of 0.5 mm and an area of ​​20 × 10 cm. 2 The lithium metal sheet is perforated, with the distance from the center point of the through hole to the end of the petal being 3mm, and the distance between the outer tangent circles of two adjacent through holes being 1mm.

[0068] Step 2: PMMA is uniformly dispersed on the porous lithium metal sheet prepared in step 1, and after filling multiple through holes, it is uniformly coated on the upper surface of the lithium metal sheet. Then, it is irradiated under ultraviolet light for 5 seconds to obtain the modified lithium metal anode material. The thickness of the PMMA layer is 30 μm.

[0069] Step 3: The LiTFSI is added dropwise to tetrahydrofuran and continuously ground to disperse it evenly, resulting in a slurry with a liquid-to-solid ratio of 20 mL / g. The slurry is then uniformly coated onto the PEO layer of the modified lithium metal anode material prepared in Step 2, and then vacuum dried at 70°C for 12 h. The resulting sheet material is the composite modified lithium metal anode material, wherein the thickness of the LiTFSI layer is 10 μm.

[0070] Example 3:

[0071] A method for preparing a composite modified lithium metal anode material includes the following steps:

[0072] Step 1: Under an argon atmosphere, use a quincunx-shaped punch to drill holes with a thickness of 3 mm and an area of ​​10 × 10 cm. 2The lithium metal sheet is perforated, with the distance from the center point of the through hole to the end of the petal being 6mm, and the distance between the outer tangent circles of two adjacent through holes being 10mm.

[0073] Step 2: PVDF-HFP is uniformly dispersed on the porous lithium metal sheet prepared in step 1. After filling multiple through holes, it is uniformly coated on the upper surface of the lithium metal sheet. Then, it is irradiated under ultraviolet light for 6 seconds to obtain the modified lithium metal anode material. The thickness of the PVDF-HFP layer is 100 μm.

[0074] Step 3: LiTFSI is added dropwise to ethyl acetate and continuously ground to disperse it evenly, resulting in a slurry with a liquid-to-solid ratio of 40 mL / g. The slurry is then uniformly coated onto the PEO layer of the modified lithium metal anode material obtained in Step 2, and then vacuum dried at 90°C for 4 hours. The resulting sheet-like material is the composite modified lithium metal anode material, wherein the thickness of the LiTFSI layer is 50 μm.

[0075] Comparative Example 1:

[0076] A method for preparing a lithium metal anode material includes: under an argon atmosphere, using a quincunx-shaped punch to drill holes with a thickness of 2 mm and an area of ​​10 × 10 cm². 2 A porous lithium metal sheet is formed by drilling holes in it. The distance from the center point of the hole to the end of the petal is 4 mm, and the distance between the center points of two adjacent holes is 10 mm. The resulting porous lithium metal sheet is the lithium metal anode material.

[0077] Comparative Example 2:

[0078] A method for preparing a composite modified lithium metal anode material includes the following steps:

[0079] Step 1: Under an argon atmosphere, uniformly disperse 1g of PEO in a solution with a thickness of 2mm and an area of ​​10×10cm. 2 The modified lithium metal anode material was obtained by irradiating it with ultraviolet light for 6 seconds on a lithium metal sheet, with a PEO layer thickness of 50 μm.

[0080] Step 2: LiTFSI is added dropwise to ethyl formate and continuously ground to disperse it evenly, resulting in a slurry with a liquid-to-solid ratio of 30 mL / g. The slurry is then uniformly coated onto the PEO layer of the modified lithium metal anode material prepared in Step 2, and then vacuum dried at 80°C for 6 hours. The resulting sheet material is the composite modified lithium metal anode material, wherein the thickness of the LiTFSI layer is 30 μm.

[0081] Example 4:

[0082] A method for preparing a modified lithium metal anode material includes the following steps:

[0083] Step 1: Under an argon atmosphere, use a quincunx-shaped punch to drill holes with a thickness of 2 mm and an area of ​​10 × 10 cm. 2 The lithium metal sheet is perforated, with the distance from the center point of the through hole to the end of the petal being 4mm, and the distance between the outer tangent circles of two adjacent through holes being 2mm.

[0084] Step 2: PEO is uniformly dispersed on the porous lithium metal sheet prepared in step 1, and after filling multiple through holes, it is uniformly coated on the upper surface of the lithium metal sheet. Then, it is irradiated under ultraviolet light for 6 seconds to obtain the modified lithium metal anode material. The thickness of the PEO layer is 50 μm.

[0085] Example 5:

[0086] A method for preparing a composite modified lithium metal anode material includes the following steps:

[0087] Step 1: Under an argon atmosphere, use a circular punch to drill a hole with a thickness of 2mm and an area of ​​10×10cm. 2 The lithium metal sheet is drilled with a radius of 4mm and a distance of 2mm between two adjacent holes.

[0088] Step 2: PEO is uniformly dispersed on the porous lithium metal sheet prepared in step 1, and after filling multiple through holes, it is uniformly coated on the upper surface of the lithium metal sheet. Then, it is irradiated under ultraviolet light for 6 seconds to obtain the modified lithium metal anode material. The thickness of the PEO layer is 50 μm.

[0089] Step 3: LiTFSI is dropped into ethyl formate and continuously ground to disperse it evenly, resulting in a slurry with a liquid-to-solid ratio of 30 mL / g. The slurry is then uniformly coated onto the PEO layer of the modified lithium metal anode material obtained in Step 2, and then vacuum dried at 80°C for 6 hours. The resulting sheet material is the composite modified lithium metal anode material, wherein the thickness of the LiTFSI layer is 30 μm.

[0090] The negative electrode materials obtained in Examples 1-4 and Comparative Examples 1-2 were stamped into a diameter of 16 mm to serve as negative electrodes. Commercial ternary materials were mixed with conductive agent acetylene black (AB) and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1, using N-methylpyrrolidone (NMP) as a solvent. The mixture was stirred at 800 r / min for 2 hours to obtain a slurry. The slurry was coated onto current collector aluminum foil using an automatic coating machine, laid flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The resulting positive electrode sheets were then stamped into a diameter of 12 mm and dried in a vacuum drying oven at 105°C for 4 hours. The sheets were then placed in a glove box filled with argon atmosphere (moisture and oxygen content both below 0.1 ppm) for 4 hours to reduce moisture adsorbed during transfer. Finally, the sheets were assembled into CR2032 coin cells in the glove box. A porous polyethylene membrane of model Celgard2300 with a diameter of 18 mm was used as the separator. In the electrolyte, the solvent was a mixed solution of DEC, EC and DMC in a volume ratio of 1:1:1, and the lithium salt was LiPF6 with a concentration of 1M.

[0091] After the battery assembly was completed and aged for 12 hours, a 1C rate charge-discharge test was then conducted at a voltage range of 3~4.3V.

[0092] Figure 1 The cycling curves of batteries assembled from the negative electrode materials obtained in Examples 1-5 and Comparative Examples 1-2 are provided by [the relevant authority / organization]. Figure 1 It is evident that drilling holes in the lithium anode effectively improves the electrochemical performance of the battery. This is because drilling increases the local potential energy, significantly increases the proportion of active components, and greatly enhances the lithium deposition rate, thereby improving electrochemical performance. Furthermore, the electrochemical stability of the battery is further improved after drilling and then combining the surface PEO layer and the lithium-based electrolyte layer. This is because the surface PEO layer smooths the lithium anode, preventing the formation of burrs during drilling that could damage the separator and cause short circuits. Additionally, the surface lithium-based electrolyte layer further promotes the rapid transport of lithium ions, thus optimizing the overall performance of the battery.

[0093] Table 1 shows the discharge specific capacity of batteries assembled from the negative electrode materials obtained in Examples 1-5 and Comparative Examples 1-2.

[0094] Table 1. Discharge specific capacity of batteries assembled from the negative electrode materials obtained in Examples 1-5 and Comparative Examples 1-2.

[0095]

[0096] Combining Table 1 and Figure 1Comparing the data of Example 1 and Comparative Example 1, Comparative Example 1 only performed the perforation process and did not set the polymer layer and lithium-based electrolyte layer. The ion conduction rate of the lithium anode was limited, and the lithium deposition was uneven, which affected the overall electrochemical performance.

[0097] Comparing the data of Example 1 and Comparative Example 2, no perforation treatment was performed in Comparative Example 2. The active ions will be concentrated on the surface layer of the lithium anode. The lithium anode does not have the advantage of local potential energy, and the proportion of active ions is greatly reduced. Although the initial electrochemical capacity is similar, the reversibility of the electrochemical capacity will be affected after later cycles.

[0098] Comparing the data of Example 1 and Example 4, Example 4 only had one PEO layer and no lithium-based electrolyte layer. The ion conduction rate of the PEO layer was low, which affected the conduction of lithium ions and thus the electrochemical performance of the battery.

[0099] Comparing the data from Examples 1 and 5, Example 1 exhibits superior electrochemical capacity reversibility, while Example 5 shows relatively poor reversibility. This may be because while the circular perforated lithium sheet improves lithium deposition capacity in the negative electrode to some extent, the improvement is limited. Furthermore, the increase in surface potential energy at the circular pores is also limited. Additionally, after passing through the composite organic polymer layer and the lithium-based electrolyte layer, capillary effects may further affect the surface potential energy at the pores. This results in the battery prepared from the circular-pore lithium sheet exhibiting lower electrochemical stability compared to the lithium sheet with the lobed perforation pattern.

[0100] The batteries assembled from the negative electrode materials prepared in Example 1, Comparative Examples 1 and 2 were subjected to further electrochemical testing at a low current of 0.1C after 100 cycles. Figure 2 This is a schematic diagram of the charging curve of the battery corresponding to Example 1; Figure 3 This is a schematic diagram of the charging curve of the battery corresponding to Comparative Example 1. Figure 4 This is a schematic diagram of the charging curve of the battery corresponding to Comparative Example 2. Figure 2 As can be seen, the battery's charging curve is smooth, and the specific charging capacity reaches 200.8 mAh / g. This indicates that the battery exhibits good reversibility after long-term cycling, with no significant capacity loss. Figure 3 It can be seen that after the battery is charged to 4.1V, the voltage drops sharply and cannot rise to the cutoff voltage of 4.3V for a long time, which indicates that a micro short circuit may occur inside the battery. Figure 4 As can be seen, the battery failed to increase its charging voltage immediately upon starting to charge, with voltage fluctuations between 2.6 and 3.0V. This indicates an internal short circuit within the battery, preventing the voltage from rising normally. In summary... Figure 2 and Figure 3 , Figure 4This further demonstrates that the negative electrode material provided by the present invention can improve the cycle reversibility of the battery and reduce the risks of battery short circuits and safety performance.

[0101] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope of the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A modified lithium metal anode material, characterized in that, It includes a lithium metal sheet and an organic polymer layer, wherein the organic polymer layer is disposed on any surface of the lithium metal sheet, and the lithium metal sheet has multiple through holes that are evenly spaced and filled with organic polymer. The distance between the outer circles of two adjacent through holes is 1~10mm; the thickness of the lithium metal sheet is 0.5~3mm; the thickness of the organic polymer layer is 30~100μm; the organic polymer is any one or more of PEO, PMMA, and PVDF-HFP.

2. The modified lithium metal anode material as described in claim 1, characterized in that, The through hole is any one or more of the following: round hole, polygonal hole, and plum blossom-shaped hole.

3. The modified lithium metal anode material as described in claim 2, characterized in that, The through hole is shaped like a plum blossom.

4. A method for preparing the modified lithium metal anode material according to any one of claims 1 to 3, characterized in that, include: Holes were drilled in a lithium metal sheet under an inert atmosphere, and then an organic polymer was filled into the holes and coated onto the surface of the lithium metal sheet, followed by curing.

5. A composite modified lithium metal anode material, characterized in that, The invention includes the modified lithium metal anode material and lithium-based electrolyte layer as described in any one of claims 1 to 3, wherein the lithium-based electrolyte layer is disposed on the surface of the organic polymer layer.

6. The composite modified lithium metal anode material as described in claim 5, characterized in that, The lithium-based electrolyte layer uses any one or more of LiTFSI, LiFSI, and LiBF4; the thickness of the lithium-based electrolyte layer is 10~50μm.

7. A method for preparing the composite modified lithium metal anode material according to any one of claims 5 to 6, characterized in that, include: A slurry is obtained by mixing a lithium-based electrolyte and a solvent. The slurry is then coated onto the surface of the organic polymer layer of the modified lithium metal anode material according to any one of claims 1 to 4, and vacuum dried to obtain the composite modified lithium metal anode material.

8. The method for preparing the composite modified lithium metal anode material as described in claim 7, characterized in that, The solvent is any one or more of tetrahydrofuran, ethyl formate, ethyl acetate, and dimethyl carbonate; the solid-liquid ratio of the slurry is 1g:20~40mL; the vacuum drying temperature is 70~90℃ and the time is 4~12h.

9. A battery, characterized in that, It includes the modified lithium metal anode material according to any one of claims 1 to 3 or the composite modified lithium metal anode material according to any one of claims 5 to 6.

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