Lithium-carbonized aluminum-zinc composite lithium metal negative electrode and preparation method and application thereof

Abstract

The application belongs to the technical field of energy storage, and discloses a lithium-aluminum carbide-zinc composite lithium metal negative electrode and a preparation method and application thereof. A multi-phase alloy phase (Li single element, Al single element, LiZn alloy, Li3Al2 alloy and Li2C2) is formed by smelting of metal lithium, aluminum carbide and zinc single element. The lithium-aluminum carbide-zinc composite lithium metal negative electrode enhances the tensile strength and controls lithium stripping and deposition due to the presence of the LiZn alloy, the Li3Al2 alloy and the Al single element. The Li2C2 carbon-containing compound enhances the mechanical toughness of the composite lithium metal negative electrode. Compared with the existing pure lithium metal negative electrode, the lithium-aluminum carbide-zinc composite lithium metal negative electrode greatly improves the tensile strength, essentially improves the mechanical performance, and this characteristic inhibits the formation of lithium dendrites in the deep stripping and deposition process of lithium.

Description

Technical Field

[0001] This application belongs to the field of energy storage technology, specifically relating to a lithium-aluminum carbide-zinc composite lithium metal anode, its preparation method, and its application. Background Technology

[0002] Lithium metal batteries, with their theoretical capacity of 3860 mAh / g for the lithium metal anode, are expected to increase battery energy density from approximately 250 Wh / kg in existing lithium-ion batteries to nearly 500 Wh / kg, enabling electric vehicles to exceed 1000 kilometers in range. However, uneven deposition during lithium deposition-stripping cycling leads to localized areas of excess or deficiency of lithium metal, causing internal stress. Furthermore, the volume expansion of lithium metal during deposition and contraction during stripping, repeated volume changes, generate mechanical stress in the lithium metal and adjacent materials. Long-term cycling can lead to material fatigue and structural damage, resulting in dendrite formation and growth, severely restricting its commercial application.

[0003] To address the dendrite growth problem in lithium metal anodes, current main strategies include current collector modification, electrode liquid engineering, alloying, and artificial SEI (Sediment Injection). For example, Chinese invention patent CN108365178B describes a protective layer formed by coating the surface of a lithium metal anode with an anionic polymer and boron nitride organic solvent. This allows for uniform lithium ion deposition on the anode surface, preventing lithium dendrites from penetrating and resulting in a stable lithium metal anode. While these strategies have suppressed dendrite growth to some extent, they do not address the fundamental stress problem faced by lithium anodes to inhibit dendrite formation. Summary of the Invention

[0004] The purpose of this application is to address the problems of the prior art by providing a lithium-aluminum carbide-zinc composite lithium metal anode, its preparation method, and its application.

[0005] To solve the technical problem, the technical solution of this application is: a method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode, comprising the following steps: Step 1: In an argon atmosphere glove box, use an electronic balance to weigh metallic lithium, aluminum carbide, and elemental zinc into stainless steel crucibles, where the mass of aluminum carbide is 2.5% to 8% of the mass of metallic lithium; and the mass of elemental zinc is 2.5% to 12% of the mass of metallic lithium. Step 2: Place the above stainless steel crucible in a muffle furnace and heat it to 400~700℃ at a heating rate of 5~10℃ / min. Hold the temperature at 400~700℃ for 3~5 hours. Then cool the muffle furnace to 300~400℃, remove it, stir and cool it, and then put it back into the muffle furnace for heating. Repeat this process 3~6 times and then pour it out to obtain the pre-made composite. Step 3: In an ultra-low dew point drying chamber with a dew point of -50~-40℃, the surface oxide of the pre-made composite is removed by a grinder, and it is pressed into a thin sheet composite by a hydraulic press. The thin sheet composite is then rolled into a composite lithium metal anode of the corresponding thickness by a rolling mill.

[0006] Preferably, in step 1, the mass of aluminum carbide is 6% to 8% of the mass of lithium metal, and the mass of elemental zinc is 6% to 8% of the mass of lithium metal.

[0007] Preferably, step 2 specifically involves: placing the stainless steel crucible from step 1 into a muffle furnace, heating it to 600°C at a heating rate of 5°C / min, holding it at 600°C for 3 hours, then cooling the muffle furnace to 400°C, removing it, stirring and cooling it, and then placing it back into the muffle furnace for heating. This process is repeated 3 times before being poured out to obtain the pre-formulated composite.

[0008] Preferably, a lithium-aluminum carbide-zinc composite lithium metal anode is prepared by the aforementioned method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode.

[0009] Preferably, an application of a lithium-aluminum carbide-zinc composite lithium metal anode is to use the composite lithium metal anode prepared by the aforementioned method in a lithium metal battery.

[0010] Preferably, the specific steps for using the composite lithium metal anode in a lithium metal battery are as follows: Step 1: In an argon atmosphere glove box, use a punching machine to punch the rolled composite lithium metal negative electrode sheet into an electrode sheet with a diameter of 10~15mm. Use the electrode sheet to assemble a symmetrical battery and match the first electrolyte. Step 2: Assemble a full battery by matching a lithium-rich manganese cathode. Use a second electrolyte. Activate the battery at 0.1C for three cycles within a voltage range of 2~4.8V, and test its cycle performance by charging at 0.2C and discharging at 1C to obtain a lithium metal battery.

[0011] Preferably, the first electrolyte is composed of a solute, a solvent, and an additive. The solute is lithium hexafluorophosphate, the solvent is a mixed solution of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and the additive is fluoroethylene carbonate. The amount of additive added is 5.0% of the total mass of the solute and solvent. The concentration of lithium hexafluorophosphate in the first electrolyte is 1.0 mol / L. The second electrolyte is an ester electrolyte.

[0012] Compared with the prior art, the advantages of this application are: (1) This application forms a multiphase alloy phase (Li element, Al element, LiZn alloy, Li3Al2 alloy and Li2C2) by melting metallic lithium, aluminum carbide and zinc elements. The lithium-aluminum carbide-zinc composite lithium metal anode has enhanced tensile strength and controlled lithium stripping and deposition due to the presence of LiZn alloy, Li3Al2 alloy and Al element. The carbon-containing compound Li2C2 enhances the mechanical toughness of the composite lithium metal anode. Compared with the existing pure lithium metal anode, the tensile strength of the lithium-aluminum carbide-zinc composite lithium metal anode is greatly improved, which essentially improves the mechanical properties. This characteristic inhibits the formation of lithium dendrites during the deep stripping and deposition process. (2) This application forms a composite lithium metal anode by melting lithium metal, aluminum carbide and zinc in one pot, which is simple to operate and can be prepared on a large scale. (3) The lithium-aluminum carbide-zinc composite lithium metal anode of this application has a high tensile strength of up to 7.0 MPa, which is much greater than that of existing pure lithium metal anodes; the lithium-aluminum carbide-zinc composite lithium metal anode of this application has a high critical current density of 12 mA cm⁻¹. -2 This is far greater than the 8mA cm of existing pure lithium metal anodes. -2 The lithium-aluminum carbide-zinc composite lithium metal anode of this application exhibits a high exchange current density, reaching 0.54 mA cm⁻¹. -2 This is far greater than the 0.23 mA cm of existing pure lithium metal anodes. -2 ; (4) The lithium-aluminum carbide-zinc composite lithium metal anode of this application has high stable cycle performance at 1 mA cm⁻¹. -2 1mAh cm -2 Under the specified conditions, the lithium-aluminum carbide-zinc composite lithium metal anode of this application can achieve stable cycling for over 700 hours, far exceeding the 400 hours of existing pure lithium metal anodes; it also achieves high current density and high stripping capacity of 3 mA cm⁻¹. -2 3mAh cm -2 Under these conditions, the lithium-aluminum carbide-zinc composite lithium metal anode of this application can achieve stable cycling for over 240 hours, which is superior to the 200 hours of existing pure lithium metal anodes; it can also achieve ultra-high current density and ultra-high stripping capacity of 5 mA cm⁻¹. -2 5mAh cm -2 Under the conditions described in this application, the lithium-aluminum carbide-zinc composite lithium metal anode can be stably cycled for over 130 hours, which is better than the 80 hours of existing pure lithium metal anodes. (5) The lithium-aluminum-zinc composite lithium metal anode of this application has excellent cycling performance in full cells. The lithium-aluminum-zinc composite lithium metal anode with an N / P ratio of 2.25 can cycle stably for more than 108 cycles, which is far better than the 44 cycles of the existing pure lithium metal anode with an N / P ratio of 2.15. Attached Figure Description

[0013] Figure 1 The image shows the XRD pattern of the lithium-aluminum carbide-zinc composite lithium metal anode in Example 1 of this application. Figure 2 The XRD pattern of an existing pure lithium metal anode is shown. Figure 3 This is a SEM image of the lithium-aluminum carbide-zinc composite lithium metal anode in Example 2 of this application. Figure 4 SEM image of an existing pure lithium metal anode; Figure 5 This is a stress-strain curve of the lithium-aluminum carbide-zinc composite lithium metal anode in Example 3 of this application; Figure 6 The stress-strain curve of an existing pure lithium metal anode is shown. Figure 7 The critical current density diagrams for the lithium-aluminum carbide-zinc composite lithium metal anode in Application Example 4 of this application and the existing pure lithium metal anode are shown. Figure 8 The diagram shows the exchange current density of the lithium-aluminum carbide-zinc composite lithium metal anode in Application Example 5 of this application and the existing pure lithium metal anode. Figure 9 The lithium-aluminum carbide-zinc composite lithium metal anode in Example 6 of this application and the existing pure lithium metal anode are compared at 1 mA cm⁻¹. -2 1 mAh cm -2 Cyclic performance under certain conditions; Figure 10 The lithium-aluminum carbide-zinc composite lithium metal anode in Example 7 of this application and the existing pure lithium metal anode are compared at 3 mA cm⁻¹. -2 3 mAh cm -2 Cyclic performance under certain conditions; Figure 11 The lithium-aluminum carbide-zinc composite lithium metal anode in Example 8 of this application and the existing pure lithium metal anode are compared at 5 mA cm⁻¹. -2 5 mAh cm -2 Cyclic performance under certain conditions; Figure 12 This application demonstrates the cycling performance of the lithium-aluminum carbide-zinc composite lithium metal anode in Example 9 of this application, which is matched with the existing pure lithium metal anode and the lithium-rich manganese cathode. Detailed Implementation

[0014] The present application is described in detail below with reference to the accompanying drawings and specific embodiments, but the present application is not limited to these embodiments. The present application covers any alternatives, modifications, equivalent methods, and solutions made within the spirit and scope of the present application. To provide the public with a thorough understanding of the present application, specific details are described in detail in the following embodiments, but those skilled in the art will fully understand the present application even without these detailed descriptions.

[0015] This application discloses a method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode, comprising the following steps: Step 1: In an argon atmosphere glove box, use an electronic balance to weigh metallic lithium, aluminum carbide, and elemental zinc into stainless steel crucibles, where the mass of aluminum carbide is 2.5% to 8% of the mass of metallic lithium; and the mass of elemental zinc is 2.5% to 12% of the mass of metallic lithium. Step 2: Place the above stainless steel crucible in a muffle furnace and heat it to 400~700℃ at a heating rate of 5~10℃ / min. Hold the temperature at 400~700℃ for 3~5 hours. Then cool the muffle furnace to 300~400℃, remove it, stir and cool it, and then put it back into the muffle furnace for heating. Repeat this process 3~6 times and then pour it out to obtain the pre-made composite. Step 3: In an ultra-low dew point drying chamber with a dew point of -50~-40℃, the surface oxide of the pre-made composite is removed by a grinder, and it is pressed into a thin sheet composite by a hydraulic press. The thin sheet composite is then rolled into a composite lithium metal anode of the corresponding thickness by a rolling mill.

[0016] Preferably, in step 1, the mass of aluminum carbide is 6% to 8% of the mass of lithium metal, and the mass of elemental zinc is 6% to 8% of the mass of lithium metal.

[0017] Preferably, step 2 specifically involves: placing the stainless steel crucible from step 1 into a muffle furnace, heating it to 600°C at a heating rate of 5°C / min, holding it at 600°C for 3 hours, then cooling the muffle furnace to 400°C, removing it, stirring and cooling it, and then placing it back into the muffle furnace for heating. This process is repeated 3 times before being poured out to obtain the pre-formulated composite.

[0018] Preferably, a lithium-aluminum carbide-zinc composite lithium metal anode is prepared by the aforementioned method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode.

[0019] Preferably, an application of a lithium-aluminum carbide-zinc composite lithium metal anode is to use the composite lithium metal anode prepared by the aforementioned method in a lithium metal battery.

[0020] Preferably, the specific steps for using the composite lithium metal anode in a lithium metal battery are as follows: Step 1: In an argon atmosphere glove box, use a punching machine to punch the rolled composite lithium metal negative electrode sheet into an electrode sheet with a diameter of 10~15mm. Use the electrode sheet to assemble a symmetrical battery and match the first electrolyte. Step 2: Assemble a full battery by matching a lithium-rich manganese cathode. Use a second electrolyte. Activate the battery at 0.1C for three cycles within a voltage range of 2~4.8V, and test its cycle performance by charging at 0.2C and discharging at 1C to obtain a lithium metal battery.

[0021] Preferably, the first electrolyte is 1.0 M LiPF6 in EC:DEC = 1:1 vol% with 5.0% FEC (the first electrolyte consists of solute, solvent and additives, the solute is lithium hexafluorophosphate LiPF6, the solvent is a mixed solution of ethylene carbonate EC and diethyl carbonate DEC in a volume ratio of 1:1, the additive is fluoroethylene carbonate FEC, the amount of additive added is 5.0% of the total mass of solute and solvent, and the concentration of lithium hexafluorophosphate in the first electrolyte is 1.0 mol / L); the second electrolyte is an ester electrolyte.

[0022] Example 1 The following is a method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode in this embodiment: Step 1: The entire smelting experiment was carried out in an argon atmosphere glove box. 5g of metallic lithium was weighed using an electronic balance, followed by the weighing of aluminum carbide (Al4C3) accounting for 5% of the metallic lithium, and then the weighing of elemental zinc accounting for 6% of the metallic lithium in a stainless steel crucible. Step 2: Place the stainless steel crucible in a muffle furnace and heat it to 600℃ at a heating rate of 5℃ / min. Hold the crucible at 600℃ for 3 hours. Then cool the muffle furnace to 400℃, remove the crucible, stir and cool it, and then put it back into the muffle furnace for heating. Repeat this process 3 times before pouring it out.

[0023] Step 3: In an ultra-low dew point drying chamber, the surface oxide of the composite prepared above is removed by a grinder, and it is pressed into a thin sheet by a hydraulic press. The thin sheet composite is then rolled into a large sheet with a thickness of 110 μm by a rolling mill to obtain a lithium-aluminum carbide-zinc composite lithium metal anode.

[0024] The application of a lithium-aluminum carbide-zinc composite lithium metal anode in this embodiment is as follows: Step 1: In an argon atmosphere glove box, use a punching machine to punch the rolled lithium-aluminum carbide-zinc composite lithium metal anode sheet into an electrode sheet with a diameter of 10mm, assemble a 2025 type symmetrical battery, and match the electrolyte 1.0M LiPF6 in EC:DEC=1:1 vol% with 5.0% FEC.

[0025] Step 2: Assemble a 2025-type full battery by matching a lithium-rich manganese cathode. The electrolyte is a self-made ester electrolyte, applied at 0.1C (C = 200 mAh g) within a voltage range of 2~4.8V. -1 The lithium metal battery was activated three times and its full-cell cycle performance was tested by charging at 0.2 C and discharging at 1C to obtain the battery.

[0026] Example 2 The following is a method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode in this embodiment: Step 1: The entire smelting experiment was carried out in an argon atmosphere glove box. 5g of metallic lithium was weighed using an electronic balance, followed by the weighing of aluminum carbide (Al4C3) accounting for 2.5% of metallic lithium, and then the weighing of elemental zinc accounting for 2.5% of metallic lithium in a stainless steel crucible. Step 2: Place the stainless steel crucible in a muffle furnace and heat it to 700℃ at a heating rate of 5℃ / min. Hold the crucible at 700℃ for 3 hours. Then cool the muffle furnace to 400℃, remove it, stir and cool it, and then put it back into the muffle furnace for heating. Repeat this process 4 times before pouring it out.

[0027] Step 3: In an ultra-low dew point drying chamber, the surface oxide of the composite prepared above is removed by a grinder, and it is pressed into a thin sheet by a hydraulic press. The thin sheet composite is then rolled into a large sheet with a thickness of 110 μm by a rolling mill to obtain a lithium-aluminum carbide-zinc composite lithium metal anode.

[0028] The application of a lithium-aluminum carbide-zinc composite lithium metal anode in this embodiment is as follows: Step 1: In an argon atmosphere glove box, use a punching machine to punch the rolled lithium-aluminum carbide-zinc composite lithium metal anode sheet into an electrode sheet with a diameter of 10mm, assemble a 2025 type symmetrical battery, and match the electrolyte 1.0M LiPF6 in EC:DEC=1:1 vol% with 5.0% FEC.

[0029] Step 2: Assemble a 2025-type full battery by matching a lithium-rich manganese cathode. The electrolyte is a self-made ester electrolyte, applied at 0.1C (C = 200 mAh g) within a voltage range of 2~4.8V. -1 The lithium metal battery was activated three times and its full-cell cycle performance was tested by charging at 0.2 C and discharging at 1C to obtain the battery.

[0030] Example 3 The following is a method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode in this embodiment: Step 1: The entire smelting experiment was carried out in an argon atmosphere glove box. 5g of metallic lithium was weighed using an electronic balance, followed by the weighing of aluminum carbide (Al4C3) accounting for 8% of the metallic lithium, and then the weighing of elemental zinc accounting for 12% of the metallic lithium in a stainless steel crucible. Step 2: Place the stainless steel crucible in a muffle furnace and heat it to 400℃ at a heating rate of 10℃ / min. Hold the crucible at 400℃ for 5 hours. Then cool the muffle furnace to 300℃, remove the crucible, stir and cool it, and then put it back into the muffle furnace for heating. Repeat this process 6 times before pouring it out.

[0031] Step 3: In an ultra-low dew point drying chamber, the surface oxide of the composite prepared above is removed by a grinder, and it is pressed into a thin sheet by a hydraulic press. The thin sheet composite is then rolled into a large sheet with a thickness of 110 μm by a rolling mill to obtain a lithium-aluminum carbide-zinc composite lithium metal anode.

[0032] The application of a lithium-aluminum carbide-zinc composite lithium metal anode in this embodiment is as follows: Step 1: In an argon atmosphere glove box, use a punching machine to punch the rolled lithium-aluminum carbide-zinc composite lithium metal anode sheet into an electrode sheet with a diameter of 10mm, assemble a 2025 type symmetrical battery, and match the electrolyte 1.0M LiPF6 in EC:DEC=1:1 vol% with 5.0% FEC.

[0033] Step 2: Assemble a 2025-type full battery by matching a lithium-rich manganese cathode. The electrolyte is a self-made ester electrolyte, applied at 0.1C (C = 200 mAh g) within a voltage range of 2~4.8V. -1 The lithium metal battery was activated three times and its full-cell cycle performance was tested by charging at 0.2 C and discharging at 1C to obtain the battery.

[0034] Application Example 1: The lithium-aluminum carbide-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode were analyzed by XRD diffraction pattern analysis.

[0035] like Figure 1 The image shown is the XRD pattern of the lithium-aluminum carbide-zinc composite lithium metal anode of this application. As can be seen from the XRD pattern, the lithium-aluminum carbide-zinc composite lithium metal anode includes elemental Li, elemental Al, LiZn alloy, Li3Al2 alloy and Li2C2. This indicates that Al4C3 reacted with elemental Li to form Li3Al2 alloy, Li2C2 and elemental Al, and Li reacted with metallic Zn to form LiZn alloy.

[0036] like Figure 2 The image shows the XRD pattern of a pure lithium metal anode. The XRD pattern only shows the characteristic diffraction peaks of Li, indicating the elemental nature of Li.

[0037] Application Example 2: The lithium-aluminum carbide-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode were examined by SEM scanning electron microscopy.

[0038] like Figure 3 The image shown is a SEM image of the lithium-aluminum carbide-zinc composite lithium metal anode of this application. The SEM image reveals a large number of particulate and rod-shaped substances in the composite anode matrix, which differs from existing pure lithium metal anodes. Figure 4 This forms a stark contrast.

[0039] like Figure 4 The image shown is a SEM image of a pure lithium metal anode. From the SEM image, it can be observed that the surface of the lithium metal anode is smooth and contains many grain boundaries.

[0040] Application Example 3: Stress-strain tests were performed on the lithium-aluminum-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode.

[0041] like Figure 5 The figure shows the stress-strain curve of the lithium-aluminum carbide-zinc composite lithium metal anode of this application. It can be observed that the tensile strength of the composite lithium metal anode is as high as 7.0 MPa, which is much greater than that of the existing pure lithium metal anode. Figure 6 ).

[0042] like Figure 6 The figure shows the stress-strain curve of a pure lithium metal anode. It can be observed that the tensile strength of the pure lithium metal anode is 1.0 MPa.

[0043] Application Example 4: The critical current density of the lithium-aluminum carbide-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode were tested.

[0044] like Figure 7 The figure shows the critical current density diagrams of the lithium-aluminum-carbide-zinc composite lithium metal anode of this application and the existing pure lithium metal anode.

[0045] The critical current densities of lithium-aluminum carbide-zinc composite lithium metal anodes and existing pure lithium metal anodes were tested using symmetrical cells. Figure 7 It can be seen that the critical current density of the lithium-aluminum carbide-zinc composite lithium metal anode in this application reaches 12 mA cm⁻¹. -2 This is far greater than the 8mA cm of existing pure lithium metal anodes. -2 .

[0046] Application Example 5: The exchange current density of the lithium-aluminum carbide-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode was measured.

[0047] like Figure 8 The figure shows the exchange current density diagram of the lithium-aluminum-carbide-zinc composite lithium metal anode of this application and the existing pure lithium metal anode.

[0048] The exchange current density of a lithium-aluminum carbide-zinc composite lithium metal anode and a conventional pure lithium metal anode was tested using a symmetrical cell. Figure 8 As can be seen, the exchange current density of the lithium-aluminum carbide-zinc composite lithium metal anode in this application reaches 0.54 mA / cm². -2 This is far greater than the 0.23 mA cm of existing pure lithium. -2 .

[0049] Application Example 6: The lithium-aluminum carbide-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode were subjected to cycle performance testing.

[0050] like Figure 9 The image shows the lithium-aluminum carbide-zinc composite lithium metal anode of this application and the existing pure lithium metal anode at 1 mA / cm². -2 1mAh cm -2 Cyclic performance under certain conditions.

[0051] At 1mA cm -2 1mAh cm -2 The cycle performance of the lithium-aluminum carbide-zinc composite lithium metal anode and the existing pure lithium metal anode were evaluated under certain conditions, such as... Figure 9 As shown, the lithium-aluminum carbide-zinc composite lithium metal anode of this application can be stably cycled for more than 700 hours, which is far superior to the 400 hours of existing pure lithium metal anodes.

[0052] Application Example 7: The lithium-aluminum carbide-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode were subjected to cycle performance testing.

[0053] like Figure 10 The image shows the lithium-aluminum carbide-zinc composite lithium metal anode of this application and the existing pure lithium metal anode at 3 mA / cm². -2 3mAh cm -2 Cyclic performance under certain conditions.

[0054] High current density, high peeling capacity 3mA cm -2 3mAh cm -2 The cycle performance of the lithium-aluminum carbide-zinc composite lithium metal anode and the existing pure lithium metal anode were evaluated under certain conditions, such as... Figure 10 As shown, the lithium-aluminum carbide-zinc composite lithium metal anode of this application can be stably cycled for more than 240 hours, which is better than the 200 hours of the existing pure lithium metal anode.

[0055] Application Example 8: The lithium-aluminum carbide-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode were subjected to cycle performance testing.

[0056] like Figure 11 The image shows the lithium-aluminum carbide-zinc composite lithium metal anode of this application and the existing pure lithium metal anode at 5 mA / cm². -2 5mAh cm -2 Cyclic performance under certain conditions.

[0057] Ultra-high current density and ultra-high stripping strength 5mA cm -2 5mAh cm -2 The cycle performance of the lithium-aluminum carbide-zinc composite lithium metal anode and the lithium metal anode was evaluated under the following conditions: Figure 11 As shown, the lithium-aluminum carbide-zinc composite lithium metal anode of this application can be stably cycled for more than 130 hours, which is better than the 80 hours of the existing pure lithium metal anode.

[0058] Application Example 9: The lithium-aluminum carbide-zinc composite lithium metal anode prepared in Example 1 and the existing pure lithium metal anode were subjected to cycle performance testing.

[0059] like Figure 12 The figure shows the cycle performance of the lithium-aluminum-carbide-zinc composite lithium metal anode of this application and the existing pure lithium metal anode matched with a lithium-rich manganese cathode.

[0060] The cycling performance of a lithium-aluminum-zinc carbide composite lithium metal anode matched with an existing pure lithium metal anode and a lithium-rich manganese cathode in a full cell was evaluated. Figure 12 As shown, the lithium-aluminum carbide-zinc composite lithium metal anode with an N / P ratio of 2.25 can stably cycle for more than 108 cycles, which is far superior to the 44 cycles of the existing pure lithium metal anode with an N / P ratio of 2.15.

[0061] The aluminum carbide in this application can be replaced with all carbides, such as TiC; the elemental Zn in this application can be replaced with all lithium-loving metal elements, such as Ag, Sn, Sb, In, Mg, etc., and all of them can be used to make composite lithium metal anodes.

[0062] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

[0063] Many other changes and modifications can be made without departing from the concept and scope of this application. It should be understood that this application is not limited to the specific embodiments, and the scope of this application is defined by the appended claims.

Claims

1. A method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode, characterized in that, Includes the following steps: Step 1: In an argon atmosphere glove box, use an electronic balance to weigh metallic lithium, aluminum carbide, and elemental zinc into stainless steel crucibles, where the mass of aluminum carbide is 2.5% to 8% of the mass of metallic lithium; and the mass of elemental zinc is 2.5% to 12% of the mass of metallic lithium. Step 2: Place the above stainless steel crucible in a muffle furnace and heat it to 400~700℃ at a heating rate of 5~10℃ / min. Hold the temperature at 400~700℃ for 3~5 hours. Then cool the muffle furnace to 300~400℃, remove it, stir and cool it, and then put it back into the muffle furnace for heating. Repeat this process 3~6 times and then pour it out to obtain the pre-made composite. Step 3: In an ultra-low dew point drying chamber with a dew point of -50~-40℃, the surface oxide of the pre-made composite is removed by a grinder, and it is pressed into a thin sheet composite by a hydraulic press. The thin sheet composite is then rolled into a composite lithium metal anode of the corresponding thickness by a rolling mill.

2. The method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode according to claim 1, characterized in that: In step 1, the mass of aluminum carbide is 6% to 8% of the mass of lithium metal, and the mass of elemental zinc is 6% to 8% of the mass of lithium metal.

3. The method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode according to claim 1, characterized in that: Step 2 specifically involves placing the stainless steel crucible from step 1 into a muffle furnace, heating it to 600°C at a rate of 5°C / min, holding it at 600°C for 3 hours, then cooling the muffle furnace to 400°C, removing it, stirring and cooling it, and then placing it back into the muffle furnace for heating. This process is repeated three times before being poured out to obtain the pre-formulated composite.

4. A lithium-aluminum carbide-zinc composite lithium metal anode, characterized in that: It is prepared by the method for preparing a lithium-aluminum carbide-zinc composite lithium metal anode as described in any one of claims 1 to 3.

5. An application of a lithium-aluminum carbide-zinc composite lithium metal anode, characterized in that: The composite lithium metal anode prepared by the method of preparing the lithium-aluminum carbide-zinc composite lithium metal anode according to any one of claims 1 to 3 is used in lithium metal batteries.

6. The application of the lithium-aluminum carbide-zinc composite lithium metal anode according to claim 5, characterized in that: The specific steps for using the composite lithium metal anode in a lithium metal battery are as follows: Step 1: In an argon atmosphere glove box, use a punching machine to punch the rolled composite lithium metal negative electrode sheet into an electrode sheet with a diameter of 10~15mm. Use the electrode sheet to assemble a symmetrical battery and match the first electrolyte. Step 2: Assemble a full battery by matching a lithium-rich manganese cathode. Use a second electrolyte. Activate the battery at 0.1C for three cycles within a voltage range of 2~4.8V, and test its cycle performance by charging at 0.2C and discharging at 1C to obtain a lithium metal battery.

7. The application of the lithium-aluminum carbide-zinc composite lithium metal anode according to claim 6, characterized in that: The first electrolyte consists of a solute, a solvent, and an additive. The solute is lithium hexafluorophosphate, the solvent is a mixed solution of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and the additive is fluoroethylene carbonate. The amount of additive added is 5.0% of the total mass of the solute and solvent. The concentration of lithium hexafluorophosphate in the first electrolyte is 1.0 mol / L. The second electrolyte is an ester electrolyte.

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