Composite lithium negative electrode material and preparation method thereof

Abstract

The application provides a composite lithium negative electrode material and a preparation method thereof, and the method comprises the following steps: under the protection of an inert atmosphere, lithium metal is heated to a completely molten state; stirring is performed in the completely molten state, and mixed powder is gradually added in the stirring process, wherein the mixed powder comprises silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide; after being uniformly mixed, natural cooling is performed to room temperature, and solidification is performed to obtain a lithium-based composite ingot; surface impurities of the lithium-based composite ingot are removed, and the lithium-based composite ingot is cut into blocks to obtain a composite lithium negative electrode; specifically, lithiumophilic metal and magnetic metal oxide are one-step constructed by a simple melting and blending method to obtain a lithium-based composite negative electrode with lithiumophilic nucleation and magnetic control transport functions; by utilizing the synergistic effect of the Lorentz force and the lithiumophilic effect, high uniformity deposition / peeling of lithium and long-acting interface self-repairing in a full solid-state battery can be realized without an external magnetic field, and the problems of lithium dendrite and interface deterioration are effectively solved.

Description

Technical Field

[0001] This invention belongs to the technical field of composite lithium anode materials, specifically relating to a composite lithium anode material and its preparation method. Background Technology

[0002] With the rapid development of new energy storage and high-end power batteries, the market is placing increasingly stringent demands on the energy density, cycle life, and safety performance of rechargeable batteries. Traditional graphite anodes, limited by their theoretical capacity, are gradually failing to meet the development needs of high-energy-density batteries. Lithium metal anodes, possessing outstanding advantages such as ultra-high theoretical specific capacity and extremely low lithium intercalation potential, are the most promising anode system for constructing high-energy-density lithium-based batteries and have broad application prospects.

[0003] However, the commercial application of pure lithium metal anodes still faces two major technological bottlenecks that urgently need to be overcome: First, the problem of disordered lithium dendrite growth. During battery charging and discharging, the uneven distribution of lithium ions on the lithium anode surface easily leads to the formation of sharp lithium dendrites. The continuous growth of these dendrites can puncture the battery separator, causing internal short circuits, thermal runaway, and fires, posing safety risks. Furthermore, dendrite shedding creates a large amount of electrochemically inactive dead lithium, resulting in severe loss of active lithium and significantly shortening battery cycle life. Second, the problem of electrode interface degradation. Lithium metal is chemically extremely reactive and readily undergoes continuous side reactions with the liquid electrolyte, forming a loosely structured, low-mechanical-strength, and poorly conductive native solid electrolyte interface film on the anode surface. This interface layer cannot adapt to the dramatic volume expansion and contraction deformation during lithium metal charging and discharging, making it prone to cracking, breakage, and repeated reconstruction. This continuously consumes electrolyte and active materials, causing a continuous increase in electrode interface impedance and a rapid decline in interface stability, ultimately leading to a degradation in battery rate performance and a sharp decrease in cycle performance.

[0004] Current technologies primarily improve the performance of lithium anodes through electrolyte formulation control, separator modification, three-dimensional current collector construction, and single surface coating modification. These optimization schemes employ limited control methods, which can only alleviate lithium dendrite growth or temporarily optimize the interface state to a limited extent. They cannot achieve precise control of lithium-ion deposition behavior and long-term stable adaptation of the electrode interface. Under long-term cycling conditions, problems such as dendrite recurrence, continuous interface degradation, and insufficient stability still exist, making them unsuitable for the actual industrial application scenarios of high-rate, long-cycle, and high-safety lithium metal batteries. Summary of the Invention

[0005] Based on this, the present invention provides a composite lithium anode material and its preparation method, which aims to achieve highly uniform lithium deposition / stripping and long-term interface self-repair in all-solid-state batteries without the need for an external magnetic field, effectively solving the problems of lithium dendrites and interface degradation.

[0006] A first aspect of this invention provides a method for preparing a composite lithium anode material, comprising the following steps: Under an inert atmosphere, lithium metal is heated until it reaches a completely molten state. The mixture is stirred in a fully molten state, and mixed powders are gradually added during the stirring process. The mixed powders include silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide. After being mixed evenly, the mixture was allowed to cool naturally to room temperature and then solidified to obtain a lithium-based composite ingot. Impurities on the surface of the lithium-based composite ingot are removed and it is cut into blocks to obtain a composite lithium anode.

[0007] Furthermore, the inert atmosphere is argon.

[0008] Furthermore, in the step of heating metallic lithium to a completely molten state under an inert atmosphere, the heating temperature is 300°C.

[0009] Furthermore, during the stirring process, a mixed powder is gradually added, the mass of which is 5% to 15% of the mass of lithium metal.

[0010] Furthermore, in the mixed powder, the mass fractions of silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide account for 1% to 3% of the mass of metallic lithium, respectively.

[0011] Furthermore, in the mixed powder, the silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide are of equal mass.

[0012] A second aspect of the present invention provides a composite lithium anode material, which is prepared by the above-described method for preparing composite lithium anode materials, wherein the composite lithium anode material is suitable for Li6PS5Cl sulfide solid electrolyte.

[0013] This invention provides a composite lithium anode material and its preparation method. Under an inert atmosphere, metallic lithium is heated to a fully molten state. While in the fully molten state, stirring is performed, and mixed powders, including silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide, are gradually added. After uniform mixing, the mixture is naturally cooled to room temperature and solidified to obtain a lithium-based composite ingot. Surface impurities are removed from the lithium-based composite ingot, and it is cut into blocks to obtain the composite lithium anode. Specifically, for the first time, a lithium-based composite anode with both lithium-affinity nucleation and magnetic transport functions is constructed in one step using a simple melt blending method with a lithium-affinity metal and a magnetic metal oxide. Utilizing the synergistic effect of Lorentz force and lithium-affinity effect, high-uniformity lithium deposition / stripping and long-term interface self-repair can be achieved in all-solid-state batteries without an external magnetic field. This effectively solves the problems of lithium dendrite formation and interface degradation, providing a novel anode design strategy for high-safety, long-life all-solid-state lithium metal batteries. Attached Figure Description

[0014] Figure 1 A flowchart illustrating a method for preparing a composite lithium anode material according to an embodiment of the present invention; Figure 2 This is a graph from a critical current density (CCD) test.

[0015] The following detailed embodiments will be further described in conjunction with the above-mentioned accompanying drawings. Detailed Implementation

[0016] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0017] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0019] Please see Figure 1 The flowchart below illustrates a method for preparing a composite lithium anode material according to an embodiment of the present invention. The method specifically includes the following steps: Step S01: Under an inert atmosphere, the lithium metal is heated until it reaches a completely molten state.

[0020] Specifically, under the protection of an argon atmosphere, metallic lithium is heated to 300°C until it reaches a completely molten state.

[0021] Step S02: Stirring is carried out in a completely molten state, and mixed powder is gradually added during the stirring process. The mixed powder includes silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide.

[0022] During the stirring process, a mixed powder is gradually added. The mass of the mixed powder is 5% to 15% of the mass of lithium metal. For example, the mass of the mixed powder is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15% of the mass of lithium metal, but it is not limited to this. It should be noted that the mass fractions of silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide are 1% to 3% of the mass of lithium metal, respectively. For example, the mass fractions of silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide are 1%, 1%, 1%, 2%, and 2% of the mass of lithium metal, respectively.

[0023] In the embodiments of the present invention, the silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide in the mixed powder are of the same mass. For example, the mass of silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide each accounts for 1% of the mass of metallic lithium.

[0024] Step S03: After mixing evenly, allow the mixture to cool naturally to room temperature and solidify to obtain a lithium-based composite ingot.

[0025] Step S04: Remove surface impurities from the lithium-based composite ingot and cut it into blocks to obtain a composite lithium anode.

[0026] Understandably, molten lithium reduces Fe₂O₃, Co₂O₃, and NiO to elemental Fe, Co, and Ni, generating lithium oxide. These nanoscale metal particles, along with silver and zinc, are uniformly dispersed within the lithium matrix. Silver and zinc, as lithiophilic components, provide abundant low nucleation barrier sites, inducing uniform nucleation and deposition of lithium ions on the negative electrode surface. Meanwhile, Fe, Co, and Ni, as ferromagnetic metals, form a localized micro-magnetic field within the negative electrode during battery charging and discharging. This field exerts a Lorentz force on moving lithium ions, promoting their spatial redistribution and suppressing tip effects and dendrite growth. If uneven deposition occurs locally, the magnetic gradient caused by changes in current density can dynamically regulate the migration direction of lithium ions, guiding excess lithium ions to other areas, thus endowing the negative electrode with self-healing capabilities.

[0027] In summary, the present invention provides a method for preparing a composite lithium anode material. This method involves heating metallic lithium to a completely molten state under an inert atmosphere; stirring the material while it is in the molten state, and gradually adding mixed powders, including silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide; after uniform mixing, naturally cooling to room temperature and solidifying to obtain a lithium-based composite ingot; removing surface impurities from the lithium-based composite ingot and cutting it into blocks to obtain a composite lithium anode. Specifically, this invention is the first to construct a lithium-based composite anode with both lithium-affinity nucleation and magnetic transport functions in one step using a simple melt blending method with a lithium-affinity metal and a magnetic metal oxide. Utilizing the synergistic effect of Lorentz force and lithium-affinity effect, high uniformity lithium deposition / stripping and long-term interface self-repair can be achieved in all-solid-state batteries without an external magnetic field, effectively solving the problems of lithium dendrite formation and interface degradation. This provides a novel anode design strategy for high-safety, long-life all-solid-state lithium metal batteries.

[0028] In another aspect, the present invention also proposes a composite lithium anode material, which is prepared by the above-described method for preparing composite lithium anode materials, wherein the composite lithium anode material is suitable for Li6PS5Cl sulfide solid electrolyte.

[0029] To facilitate understanding of the present invention, several embodiments are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0030] Example 1 In Embodiment 1 of the present invention, 0.2g of metallic lithium was heated to 300°C under an argon atmosphere to reach a completely molten state; The mixture is stirred in a fully molten state, and 5% of the mass of lithium metal is gradually added during the stirring process. That is, the mass of the added mixed powder is 0.01g. The mixed powder includes silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide, and the mass of silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide is the same, which is 0.002g. After being mixed evenly, the mixture was allowed to cool naturally to room temperature and then solidified to obtain a lithium-based composite ingot. Impurities on the surface of the lithium-based composite ingot are removed and it is cut into blocks to obtain a composite lithium anode.

[0031] Example 2 The difference between the preparation method in Example 2 and that in Example 1 is that the stirring is carried out in a completely molten state, and 10% of the mass of lithium metal powder is gradually added during the stirring process, that is, the mass of the added mixed powder is 0.02g. The mixed powder includes silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide, and the mass of silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide is the same, all being 0.004g, that is, the mass of each material accounts for 2% of the mass of lithium metal.

[0032] Testing showed that the composite lithium metal anode prepared in Example 2 of this invention exhibited excellent critical current density (CCD) performance, reaching 4 mA cm⁻¹. -2 It also exhibits significant self-healing effects. At 0.5 mA cm -2 Under current density, the polarization voltage exhibits a trend of first decreasing and then increasing, such as Figure 2 As shown, the critical current density (CCD) test results are attributed to the synergistic effect of lithiophilic nucleation and magnetron transport, which enables uniform lithium deposition / stripping and dynamic self-healing of the interface.

[0033] Example 3 The difference between the preparation method in Example 3 and that in Example 2 is that 0.2g of metallic lithium is heated to 200°C under an argon atmosphere to reach a completely molten state.

[0034] Example 4 The difference between the preparation method in Example 4 and that in Example 2 is that 0.2g of metallic lithium is heated to 400°C under an argon atmosphere to reach a completely molten state.

[0035] Example 5 The difference between the preparation method in Example 5 and that in Example 2 is that the mass ratio of silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide in the mixed powder is 2:2:1:1:1, that is, 0.0057g of silver powder and zinc powder, and 0.00285g of iron oxide, cobalt oxide and nickel oxide.

[0036] Example 6 The difference between the preparation method in Example 6 and that in Example 2 is that the mass ratio of silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide in the mixed powder is 1:1:2:2:2, with 0.005g of silver powder and zinc powder, and 0.0025g of iron oxide, cobalt oxide and nickel oxide.

[0037] It should be noted that the sample heated to 200℃ is close to the low melting temperature range of lithium metal, resulting in weak fluidity of the molten lithium and limited uniformity of the mixed powder dispersion. The sample heated to 300℃ has sufficient melting, good fluidity of the system, and uniform dispersion of the mixed powder, which is conducive to the formation of uniform lithium-affinity nucleation sites and locally magnetically modulated components. The sample heated to 400℃ has higher melt fluidity, but the excessively high temperature exacerbates the reaction between molten lithium and some metal oxides and increases the risk of surface impurity formation.

[0038] Comparative analysis showed that the composite lithium anode material prepared at 300℃ exhibited the best overall performance, demonstrating optimal lithium deposition / exfoliation stability and controllable interfacial side reactions. Therefore, a suitable melting temperature of 300℃ is appropriate, ensuring sufficient melting and uniform dispersion while avoiding interfacial degradation caused by excessively high temperatures.

[0039] In addition, when the mass ratio of silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide is 1:1:1:1:1, the lithiophilic component and the magnetic oxide component are balanced, which is conducive to the synergistic effect of lithiophilic nucleation induction and local magnetic transport regulation. When the mass ratio is 2:2:1:1:1, the content of lithiophilic component increases, which can provide more nucleation sites, reduce the initial nucleation overpotential, and improve the initial deposition distribution of lithium. When the mass ratio is 1:1:2:2:2, the content of magnetic oxide component increases, which enhances the local magnetic regulation effect, but the lithiophilic nucleation sites are relatively reduced, which may affect the uniform nucleation in the initial deposition stage.

[0040] Comparative analysis showed that the sample with a mass ratio of 1:1:1:1:1 exhibited the best match between lithiophilic nucleation and magnetic modulation, resulting in optimal lithium deposition / stripping stability. While the sample with a mass ratio of 2:2:1:1:1 had a lower nucleation overpotential, its magnetron sputtering effect was slightly insufficient during long-term cycling. The sample with a mass ratio of 1:1:2:2:2 demonstrated enhanced magnetron sputtering but reduced initial deposition uniformity. Therefore, the optimal component ratio was determined by adding silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide by mass.

[0041] In summary, the composite lithium anode material and its preparation method proposed in this invention involve heating metallic lithium to a completely molten state under an inert atmosphere; stirring the material while it is in the completely molten state, and gradually adding mixed powders, including silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide; after uniform mixing, naturally cooling to room temperature and solidifying to obtain a lithium-based composite ingot; removing surface impurities from the lithium-based composite ingot and cutting it into blocks to obtain the composite lithium anode. Specifically, this invention is the first to construct a lithium-based composite anode with both lithium-affinity nucleation and magnetic transport functions in one step using a simple melt blending method with a lithium-affinity metal and a magnetic metal oxide. Utilizing the synergistic effect of Lorentz force and lithium-affinity effect, high uniformity lithium deposition / stripping and long-term interface self-repair can be achieved in all-solid-state batteries without the need for an external magnetic field, effectively solving the problems of lithium dendrites and interface degradation, and providing a novel anode design strategy for high-safety, long-life all-solid-state lithium metal batteries.

[0042] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a composite lithium anode material, characterized in that, Includes the following steps: Under an inert atmosphere, lithium metal is heated until it reaches a completely molten state. The mixture is stirred in a fully molten state, and mixed powders are gradually added during the stirring process. The mixed powders include silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide. After being mixed evenly, the mixture was allowed to cool naturally to room temperature and then solidified to obtain a lithium-based composite ingot. Impurities on the surface of the lithium-based composite ingot are removed and it is cut into blocks to obtain a composite lithium anode.

2. The method for preparing the composite lithium anode material according to claim 1, characterized in that, The inert atmosphere is argon.

3. The method for preparing the composite lithium anode material according to claim 1, characterized in that, In the step of heating metallic lithium to a completely molten state under an inert atmosphere, the heating temperature is 300°C.

4. The method for preparing the composite lithium anode material according to claim 1, characterized in that, During the stirring process, the mixed powder is gradually added, and the mass of the mixed powder is 5% to 15% of the mass of lithium metal.

5. The method for preparing the composite lithium anode material according to claim 4, characterized in that, In the mixed powder, the mass fractions of silver powder, zinc powder, iron oxide, cobalt oxide and nickel oxide are 1% to 3% of the mass of lithium metal, respectively.

6. The method for preparing the composite lithium anode material according to claim 5, characterized in that, In the mixed powder, the silver powder, zinc powder, iron oxide, cobalt oxide, and nickel oxide are of equal mass.

7. A composite lithium anode material, characterized in that, The composite lithium anode material is prepared by the preparation method of any one of claims 1-6, wherein the composite lithium anode material is suitable for Li6PS5Cl sulfide solid electrolyte.

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