Multi-layer single-orientation current collector, preparation method and high-specific-energy lithium battery for flight power

Abstract

The invention discloses a multi-layer single-orientation current collector, a preparation method and a high-specific-energy lithium battery for flight power, and the preparation method comprises the following steps: S1, selecting a proper metal substrate for surface pretreatment, placing the pretreated metal substrate in an annealing furnace, annealing by using a mixed atmosphere of hydrogen and inert gas, or carrying out electro-deposition on the metal substrate to obtain a multi-layer single-orientation current collector; obtaining a metal substrate with single crystal face orientation; and S2, an alloy layer with the single orientation is formed on the surface of the metal substrate with the single orientation through induction, the crystal face orientation of the alloy layer is {111}, {200} or {220}, and the purity of the crystal face orientation is not lower than 90%. A single-orientation lithium deposition induction layer can be induced to be generated on a single-orientation current collector base material, a multi-layer single-orientation structure is formed, on one hand, nucleation energy barriers can be reduced through the characteristics of the induction layer, and uniform deposition of lithium is promoted; on the other hand, ordered crystal arrangement in the single orientation structure of the layer is beneficial to electron conduction, and lithium deposition and separation are promoted.

Description

Technical Field

[0001] This invention relates to the field of current collector materials technology, and in particular to multilayer unidirectional current collectors and their preparation methods, and high-energy-density lithium batteries for flight propulsion. Background Technology

[0002] Lithium (Li) metal batteries are considered one of the most promising rechargeable lithium-based batteries due to their extremely high energy density. The lithium metal anode possesses an extremely high theoretical specific capacity (3860 mAh·g). -1 Its low operating potential (-3.04 V) makes it ideal for high-energy-density battery systems. To fully explore the advantages of high energy density, there is an urgent need to integrate ultrathin lithium metal anodes (e.g., < 25 μm) or even initially lithium-free anodes. However, ultrathin lithium metal anodes have poor machinability, high chemical reactivity with moisture and oxygen under environmental conditions, and poor electrochemical reversibility.

[0003] To overcome the aforementioned problems, batteries with initially lithium-free anodes avoid the direct use of metallic lithium, leading to the development of initially lithium-free anode technology. These batteries do not contain metallic lithium initially; instead, active lithium is provided by the positive electrode during charging. During charging, lithium is stripped from the positive electrode and deposited onto the negative electrode current collector, and then stripped back onto the positive electrode during subsequent discharge. This design effectively improves battery safety, reduces manufacturing complexity, and helps maximize battery energy density. However, the reversibility of lithium deposition / stripping on the negative electrode current collector is crucial to the battery's cycle life.

[0004] Lithium deposition involves nucleation and growth, typically occurring preferentially at sites with lower nucleation barriers. Traditionally, copper foil has been widely used as a current collector in lithium-free anodes. However, due to the weak affinity of copper for lithium and its high interfacial impedance, lithium deposition is uneven, easily forming dendrites that can puncture the separator, leading to short circuits and safety risks. To address this issue, researchers have modified copper foil in various ways, for example: Induced metal plating: Patent document CN111969212A proposes to plate a metal layer on the surface of a copper current collector that can form an alloy with lithium to reduce the overpotential of lithium deposition, induce uniform lithium deposition, thereby suppressing dendrite growth and improving cycle stability.

[0005] Three-dimensional lithiophilic layer structure: Patent document CN116190559B discloses a method for constructing a three-dimensional (3D) lithiophilic layer on the surface of copper foil. This structure can increase the specific surface area of ​​the current collector, alleviate the volume change during the lithium insertion / extraction process, reduce the local current density, and promote the uniform deposition of lithium.

[0006] While the aforementioned methods optimize lithium deposition behavior to some extent, they primarily focus on introducing other components onto the copper current collector surface, neglecting the influence of the current collector's own crystal structure on lithium deposition. It is well known that conventional current collectors are multi-oriented crystals, and different crystal facets have varying affinities for lithium. Facets with higher affinity exhibit lower overpotentials, inducing uniform lithium deposition and thus suppressing lithium dendrite growth. These methods, however, ignore the influence of different crystal facets; although the coating can suppress dendrite growth, the effect is very limited.

[0007] Therefore, designing a single-orientation current collector with high affinity for lithium can improve the cycle stability and lifespan of the battery. Summary of the Invention

[0008] The purpose of this invention is to provide a multilayer single-orientation current collector and its preparation method, as well as a high-energy-density lithium battery for flight propulsion. A single-orientation lithium deposition induction layer can be induced on the single-orientation current collector substrate to form a multilayer single-orientation structure. On the one hand, the characteristics of the induction layer itself can reduce the nucleation energy barrier and promote uniform lithium deposition; on the other hand, the ordered crystal arrangement in the single-orientation structure is conducive to electron conduction, promoting lithium deposition and extraction.

[0009] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A method for preparing a multilayer unidirectional current collector includes the following steps: S1. Select a suitable metal substrate for surface pretreatment, place the pretreated metal substrate in an annealing furnace, and anneal it using a mixed atmosphere of hydrogen and inert gas, or perform electrodeposition on the metal substrate to obtain a metal substrate with a single crystal plane orientation. S2. On the surface of a metal substrate with a single orientation, an alloy layer with a single orientation is induced to form, wherein the crystal orientation of the alloy layer is {111}, {200} or {220}, and the purity of the crystal orientation is not less than 90%.

[0010] Preferably, the metal substrate is selected from copper, aluminum, nickel, titanium, and silver, and the thickness of the metal substrate is 10 μm to 50 μm.

[0011] Preferably, the annealing conditions in step S1 are as follows: When the metal substrate is copper foil, apply a pressure of 220 MPa to the copper foil once, raise the temperature to 450°C at a heating rate of 5°C / min to 10°C / min, and hold for 4 hours; When the metal substrate is aluminum foil, apply a pressure of 380 MPa twice to the aluminum foil, raise the temperature to 600°C at a heating rate of 5°C / min to 10°C / min, and hold for 4 hours; When the metal substrate is nickel foil, apply a pressure of 550 MPa three times to the nickel foil, raise the temperature to 1000°C at a heating rate of 5°C / min to 10°C / min, and hold for 6 hours. When the metal substrate is titanium foil, apply a pressure of 500 MPa to the titanium foil once, raise the temperature to 750°C at a heating rate of 5°C / min to 10°C / min, and hold for 5 hours. When the metal substrate is silver foil, a pressure of 220 MPa is applied to the silver foil once, and the temperature is raised to 380°C at a heating rate of 5°C / min to 8°C / min and held for 4.5 hours to obtain a metal substrate with a single crystal plane orientation.

[0012] Preferably, the thickness of the alloy layer is 1 μm to 10 μm.

[0013] Preferably, the alloy layer composition includes a substance with a Gibbs free energy of less than zero that undergoes an alloying reaction with the metal substrate.

[0014] Preferably, the alloy layer composition includes a combination of two metals selected from copper, lithium, manganese, tin, aluminum, nickel, silver, zinc, molybdenum, titanium, cobalt, and magnesium.

[0015] Preferably, the alloy layer is prepared by chemical deposition, electrodeposition, atomic layer deposition, hydrothermal synthesis, magnetron sputtering, and ion sputtering.

[0016] The multilayer unidirectional current collector was prepared using the method described above.

[0017] A high-energy-density lithium battery for flight propulsion employs the aforementioned multilayer unidirectional current collector.

[0018] Compared with the prior art, the advantages of the present invention are as follows: 1. Using a multilayer single-oriented alloy material as the current collector effectively promotes the uniform deposition and extraction of lithium ions, avoiding the growth of lithium dendrites, thereby significantly improving the cycle stability and lifespan of the battery. This material can maintain a low polarization voltage during high-rate charge and discharge, enhancing the battery's high-power output capability; 2. By precisely controlling the crystal orientation of the alloy layer (e.g., {111}, {200}, {220}), the purity of the selected crystal orientation is ensured to be no less than 90%, optimizing the electrochemical reaction rate of the battery and improving the battery efficiency during charging and discharging. Compared with traditional polycrystalline current collectors, single-orientation alloy materials have better conductivity and higher battery capacity retention.

[0019] 3. The preparation method is applicable to various metal substrates, such as copper, aluminum, nickel, titanium, and silver, with substrate thickness ranging from 10 μm to 50 μm. This makes the technology widely applicable in different types of batteries, meeting diverse battery requirements. The composition of the alloy layer can be flexibly adjusted according to needs, including combinations of metals such as copper, zinc, aluminum, and nickel. This allows for customization of the material's electrochemical properties to meet different battery requirements, further improving battery performance.

[0020] 4. A single-oriented lithium deposition induction layer can be induced on a single-oriented current collector substrate, forming a multi-layer single-oriented structure. On the one hand, the characteristics of the induction layer itself can reduce the nucleation energy barrier and promote uniform lithium deposition; on the other hand, the ordered crystal arrangement in the single-oriented structure is conducive to electron conduction, promoting lithium deposition and extraction.

[0021] 5. Single-oriented alloy current collectors are prepared by combining heating rate and pressure. The heating rate determines the rate of temperature change of the metal substrate during annealing. A slower heating rate (e.g., 5℃ / min to 10℃ / min) reduces the influence of temperature gradient and thermal stress, thus helping the metal substrate achieve uniform grain growth during heating. During annealing, the metal grains gradually orient themselves, eventually forming a single crystal orientation. This slow heating rate helps avoid uneven grain distribution or localized overheating caused by rapid temperature changes in the metal substrate, thus ensuring a more uniform and consistent crystal orientation of the alloy material. Applying appropriate pressure can generate additional mechanical stress during annealing, promoting grain movement and rearrangement. By applying pressure, the grains of the metal substrate can be effectively induced to align in a specific direction during annealing, enhancing the single crystal orientation of the metal substrate. The introduction of pressure can start stimulating grain growth and orientation at lower temperatures, helping the metal achieve a more regular structure at the grain level.

[0022] Applying pressure facilitates grain fusion and growth in the metal substrate during annealing. Appropriate pressure brings grains closer together and allows them to interact, preventing grain boundary defects and improving the integrity of the material's crystal structure. Simultaneously, a slower heating rate helps maintain a uniform grain distribution during growth, avoiding grain size variations caused by excessively rapid temperature increases, thus improving the structural uniformity of the alloy material.

[0023] During annealing, the combination of heating rate and applied pressure facilitates the directional growth of crystals. As the temperature rises, grains in the metal substrate gradually tend towards the orientation with the lowest surface energy. Appropriate pressure can promote grain growth towards a direction with a single crystal plane orientation, while a slow heating rate can prevent uneven grain orientation under thermal stress. Combining these two factors can improve the purity of the single crystal plane orientation, achieving at least 90% crystal plane orientation, thereby ensuring the excellent performance of the alloy material in batteries.

[0024] Therefore, the coordination of heating rate and applied pressure plays a crucial role in the preparation of single-oriented alloy current collector materials. By controlling grain growth, directional growth, and defect reduction, they help obtain high-quality single-oriented alloy layers, thereby significantly improving the conductivity, mechanical strength, and overall battery performance of the current collector material. This optimized annealing process provides strong technical support for the realization of high-performance lithium-free anode batteries. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 XRD curves of Cu{200} with a single orientation and sample 1.

[0027] Figure 2 The XRD curve of Cu{200} sample 2 with a single orientation is shown.

[0028] Figure 3 The XRD curve of Cu{220} sample 3 with a single orientation.

[0029] Figure 4 The images show in-situ dendrite observations of samples 1, 2, and 4. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] Example 1 In this embodiment, a multilayer unidirectional current collector was prepared, using copper foil as the metal substrate.

[0032] The specific steps are as follows: Step S1: Select a 30μm thick copper foil substrate. First, immerse the copper foil in an ethanol solution for ultrasonic cleaning for 30 minutes to remove surface dirt. After vacuum drying, prepare a single-oriented copper foil.

[0033] The treated copper foil was placed in a tube furnace and heated to 450°C at a heating rate of 10°C / min under a mixed atmosphere of H2 / Ar (where H2 is 5 vol%). The temperature was held for 4 hours. During the heating process or while maintaining the temperature at 450°C, a pressure of 220 MPa was applied once. After annealing, a single-crystal-oriented copper substrate {200} was obtained.

[0034] Step S2: On a single-oriented copper substrate surface, with a background vacuum of 1.8*10 -5 Silver target magnetron sputtering was performed under the conditions of working gas pressure of 0.3 Pa, voltage of 320 V, and current of 0.05 A, with a deposition rate of approximately 2.06 nm / min and sputtering time of 1 h. This induced the formation of an alloy layer with a single orientation, resulting in a double-layer single-crystal current collector foil (copper {200}@silver {111}). The crystal orientation of the alloy layer is {111}, and the purity of the crystal orientation is not less than 90%.

[0035] The foil was punched into small round sheets of 16mm. In a glove box, it was assembled with electrolyte and NCM811 to form a lithium-free negative electrode coin cell, thus obtaining sample 1.

[0036] Example 2 In this embodiment, a multilayer unidirectional current collector is prepared, and the specific steps are as follows: Step S1: Select a 30μm thick copper foil substrate. First, immerse the copper foil in an ethanol solution for ultrasonic cleaning for 30 minutes to remove surface dirt. After vacuum drying, prepare a single-oriented copper foil.

[0037] The treated copper foil was placed in a tube furnace and heated to 450°C at a heating rate of 10°C / min under a mixed atmosphere of H2 / Ar (where H2 is 5 vol%). The temperature was held for 4 hours. During the heating process or while maintaining the temperature at 450°C, a pressure of 220 MPa was applied once. After annealing, a single-crystal-oriented copper substrate {200} was obtained.

[0038] Step S2: Immerse a single-oriented copper {200} layer in a tin plating solution and hold for 1 minute to obtain a double-layer single-oriented current collector foil (tin {101}@copper {200}). The crystal orientation of the alloy layer is {200}, and the purity of the crystal orientation is not less than 90%.

[0039] The foil was punched into small round pieces of 16mm. In a glove box, it was assembled with electrolyte and NCM811 to form a lithium-free negative electrode coin cell, thus obtaining sample 2.

[0040] Example 3 In this embodiment, a multilayer unidirectional current collector is prepared, and the specific steps are as follows: Step S1: Select a 30μm thick copper foil substrate. First, immerse the copper foil in an ethanol solution for ultrasonic cleaning for 30 minutes to remove surface dirt. After vacuum drying, prepare a single-oriented copper foil.

[0041] The treated copper foil was placed in an electrolytic cell as the anode, and a steel plate as the cathode. The electrolyte consisted of 200 g / L CuSO4, 80 g / L H2SO4, 0.1 g / L sodium 3-mercaptopropanesulfonate, and 0.2 g / L NaCl. The electrolyte concentration was 120 mA / cm². 2 Copper {220} with a single crystal plane orientation was obtained by electrolysis for 12 min at a current density.

[0042] Step S2: Immerse a single-oriented copper {200} layer in the zinc plating solution and hold for 2 minutes to obtain a double-layer single-crystal current collector foil (zinc {103})@copper {200}. The crystal orientation of the alloy layer is {200}, and the purity of the crystal orientation is not less than 90%.

[0043] The foil was punched into small round pieces of 16mm. In a glove box, it was assembled with electrolyte and NCM811 to form a lithium-free negative electrode coin cell, resulting in sample 3.

[0044] Comparative Example 1 The copper foil was ultrasonically cleaned in an ethanol solution for 30 minutes, then vacuum dried for later use. The treated copper foil had a background vacuum of 1.8*10⁻⁶. -5 Silver target magnetron sputtering was performed under the conditions of working gas pressure of 0.3 Pa, voltage of 320 V, and current of 0.05 A, with a deposition rate of approximately 2.06 nm / min and a sputtering time of 1 h, to obtain a double-layer current collector foil.

[0045] The foil was punched into small round pieces of 16mm. In a glove box, it was assembled with electrolyte and NCM811 to form a lithium-free negative electrode coin cell, resulting in sample 4.

[0046] Comparative Example 2 The copper foil was ultrasonically cleaned in an ethanol solution for 30 minutes and then vacuum dried for later use. The treated copper foil was then immersed in a tin plating solution for 1 minute to obtain a double-layer current collector foil.

[0047] The foil was punched into small round pieces of 16mm. In a glove box, it was assembled with electrolyte and NCM811 to form a lithium-free negative electrode coin cell, resulting in sample 5.

[0048] Cyclic performance test: The batteries assembled using Examples 1-3 and Comparative Examples 1-2 were subjected to cycle performance tests.

[0049] Test method: The lithium metal battery pack was charged and discharged at a charging rate of 0.33C / 0.33C. After 150 cycles, the capacity retention rate was recorded.

[0050] name <![CDATA[Initial cycle discharge specific capacity mAh / g -1 > Number of cycles Capacity retention rate % Sample 1 219.25 150 89.31 Sample 2 205.64 150 76.56 Sample 3 202.15 150 68.25 Sample 4 189.358 150 44.17 Sample 5 189.68 150 35.62 Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a multilayer unidirectional current collector, characterized in that, Includes the following steps: S1. Select a suitable metal substrate for surface pretreatment, place the pretreated metal substrate in an annealing furnace, and anneal it using a mixed atmosphere of hydrogen and inert gas, or perform electrodeposition on the metal substrate to obtain a metal substrate with a single crystal plane orientation. S2. On the surface of a metal substrate with a single orientation, an alloy layer with a single orientation is induced to form, wherein the crystal orientation of the alloy layer is {111}, {200} or {220}, and the purity of the crystal orientation is not less than 90%.

2. The method for preparing a multilayer unidirectional current collector according to claim 1, characterized in that, The metal substrate is selected from copper, aluminum, nickel, titanium, and silver, and the thickness of the metal substrate is 10 μm to 50 μm.

3. The method for preparing a multilayer unidirectional current collector according to claim 2, characterized in that, The annealing conditions in step S1 are specifically as follows: When the metal substrate is copper foil, apply a pressure of 220 MPa to the copper foil once, raise the temperature to 450°C at a heating rate of 5°C / min to 10°C / min, and hold for 4 hours; When the metal substrate is aluminum foil, apply a pressure of 380 MPa twice to the aluminum foil, raise the temperature to 600°C at a heating rate of 5°C / min to 10°C / min, and hold for 4 hours; When the metal substrate is nickel foil, apply a pressure of 550 MPa three times to the nickel foil, raise the temperature to 1000°C at a heating rate of 5°C / min to 10°C / min, and hold for 6 hours. When the metal substrate is titanium foil, apply a pressure of 500 MPa to the titanium foil once, raise the temperature to 750°C at a heating rate of 5°C / min to 10°C / min, and hold for 5 hours. When the metal substrate is silver foil, a pressure of 220 MPa is applied to the silver foil once, and the temperature is raised to 380°C at a heating rate of 5°C / min to 8°C / min and held for 4.5 hours to obtain a metal substrate with a single crystal plane orientation.

4. The method for preparing a multilayer unidirectional current collector according to claim 1, characterized in that, The thickness of the alloy layer is 1 μm to 10 μm.

5. The method for preparing a multilayer unidirectional current collector according to claim 1, characterized in that, The alloy layer composition includes substances with a Gibbs free energy of less than zero that undergo alloying reactions with the metal substrate.

6. The method for preparing a multilayer unidirectional current collector according to claim 5, characterized in that, The alloy layer composition includes a combination of two metals selected from copper, lithium, manganese, tin, aluminum, nickel, silver, zinc, molybdenum, titanium, cobalt, and magnesium.

7. The method for preparing a multilayer unidirectional current collector according to claim 1, characterized in that, The alloy layer is prepared by chemical deposition, electrodeposition, atomic layer deposition, hydrothermal synthesis, magnetron sputtering and ion sputtering.

8. A multilayer unidirectional current collector, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. A high-energy-density lithium battery for flight propulsion, characterized in that, The multilayer unidirectional current collector as described in claim 8 is used.

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