Aluminum current collector for sodium battery without negative electrode, preparation method thereof and sodium battery without negative electrode

Abstract

This invention discloses an aluminum current collector for a negative electrode-free sodium-ion battery, its preparation method, and the negative electrode-free sodium-ion battery itself, relating to the field of negative electrode-free sodium-ion battery technology. The aluminum current collector for a negative electrode-free sodium-ion battery provided by this invention comprises a three-layer structure: a three-dimensional porous aluminum substrate, a zinc-aluminum alloy layer, and a zinc functional layer. The thicknesses of the zinc-aluminum alloy layer and the zinc functional layer are optimized. The zinc-aluminum alloy layer buffers expansion stress, while the zinc functional layer provides sodium-affinity alloying sites. The aluminum current collector for a negative electrode-free sodium-ion battery provided by this invention has the following advantages: it effectively solves the problem of cyclic peeling failure of the magnetron sputtered zinc layer, significantly improving the interfacial bonding force between the zinc layer and the porous aluminum; it achieves metallurgical bonding and mechanical interlocking between the zinc layer and the aluminum substrate, adapting to repeated expansion and contraction of the zinc-sodium alloy; and it maintains the three-dimensional porous structure without clogging, improving the cycle stability and long-term sodium affinity of the negative electrode-free sodium-ion battery.

Description

Technical Field

[0001] This invention relates to the field of negative electrode-free sodium-ion battery technology, and more specifically, to aluminum current collectors for negative electrode-free sodium-ion batteries, their preparation methods, and negative electrode-free sodium-ion batteries. Background Technology

[0002] Electrodeless sodium-ion batteries eliminate the need for a pre-placed metallic sodium anode. During charging, sodium ions are directly deposited in situ on the surface of the anode current collector to form a sodium metallic anode. This technology boasts advantages such as high energy density and low cost, making it a core technology for next-generation energy storage. Currently, however, electrodeless batteries face significant technical bottlenecks with their anode current collectors: conventional dense aluminum foil has a smooth surface and poor sodium affinity, resulting in a high sodium nucleation overpotential and a tendency for localized concentrated deposition. This can induce sodium dendrites and dead sodium accumulation, and the poor reversibility of deposition and dissolution severely shortens cycle life.

[0003] Existing three-dimensional porous aluminum current collectors rely solely on their physical porous structure to disperse current and buffer volume expansion. However, aluminum's intrinsic sodium affinity is weak, and uneven ion distribution and localized current concentration still exist within the pores, failing to intrinsically improve sodium nucleation behavior. To enhance sodium affinity, a magnetron sputtering metal coating scheme using a three-dimensional porous aluminum current collector is employed. While this scheme can improve sodium affinity and suppress dendrites, it still suffers from the following drawbacks: (1) Conventional magnetron sputtering is a physical adhesion process, and the bonding force between the metal coating and the aluminum skeleton is extremely low; (2) After charging, the metal alloy with sodium expands in volume, and the coating peels off and pulverizes rapidly during charge and discharge cycles; (3) After the coating fails, the sodium affinity disappears, sodium deposition becomes uneven, dendrites regenerate, and battery life decreases.

[0004] Therefore, it is urgent to solve the problem of metal coating expansion and peeling in order to improve battery life.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an aluminum current collector for a negative electrode-free sodium battery, a method for preparing the same, and a negative electrode-free sodium battery, aiming to solve the problem of metal coating expansion and peeling, thereby improving battery life.

[0007] This invention is implemented as follows: In a first aspect, the present invention provides an aluminum current collector for a negative electrode-free sodium battery, comprising a three-dimensional porous aluminum substrate, wherein a zinc-aluminum alloy layer and a zinc functional layer are sequentially deposited on the three-dimensional porous aluminum substrate. The thickness of the zinc-aluminum alloy layer is 10nm~50nm, and the thickness of the zinc functional layer is 50nm~500nm.

[0008] In an optional embodiment, the thickness of the zinc-aluminum alloy layer is 20nm~40nm, and the thickness of the zinc functional layer is 100nm~300nm. And / or, the molar ratio of zinc to aluminum in the zinc-aluminum alloy layer is 1:(0.3~1.2).

[0009] In an optional embodiment, the thickness of the three-dimensional porous aluminum substrate is 20 μm to 40 μm, the pore size is 1 μm to 5 μm, and the porosity is 70% to 90%.

[0010] Secondly, the present invention provides a method for preparing an aluminum current collector for a non-negative electrode sodium battery according to any of the foregoing embodiments, comprising: sequentially depositing a zinc-aluminum alloy layer and a zinc functional layer on a three-dimensional porous aluminum substrate.

[0011] In an optional embodiment, a zinc-aluminum alloy layer and a zinc functional layer are deposited by magnetron sputtering, with the background vacuum controlled at 1×10⁻⁶ during the deposition process. -4 Pa ~5×10 -4 Pa, working air pressure is 0.4Pa~0.7Pa.

[0012] In an optional embodiment, during the deposition of the zinc-aluminum alloy layer, a Zn-Al alloy target is used, the sputtering power is 80W~200W, the target-substrate distance is 80mm~120mm, the substrate temperature is 25℃~80℃, and the substrate negative bias voltage is -50V~-150V.

[0013] In an optional embodiment, during the deposition of the zinc functional layer, a pure zinc target is used, the sputtering power is 100W~250W, the target-substrate distance is 80mm~120mm, the substrate temperature is 25℃~80℃, and the substrate negative bias voltage is -30V~-100V.

[0014] In an optional embodiment, after depositing the zinc-aluminum alloy layer and the zinc functional layer, low-temperature vacuum annealing is performed, with the vacuum controlled to be ≤1×10⁻⁶. -3 Pa, annealing temperature is 200℃~400℃, holding time is 30min~60min.

[0015] In an optional embodiment, the three-dimensional porous aluminum substrate is pretreated and plasma etched before depositing the zinc-aluminum alloy layer and the zinc functional layer. The pretreatment steps include: cleaning and drying the three-dimensional porous aluminum substrate; the solvent used for cleaning is an organic alcohol solvent. During the plasma etching process, argon plasma etching is used, and the etching time is 2 min to 5 min.

[0016] Thirdly, the present invention provides a non-negative electrode sodium battery, comprising any of the aluminum current collectors for non-negative electrode sodium batteries in the foregoing embodiments or aluminum current collectors for non-negative electrode sodium batteries prepared by any of the preparation methods in the foregoing embodiments.

[0017] The present invention has the following beneficial effects: The aluminum current collector for sodium-ion batteries without negative electrodes provided by the present invention comprises a three-layer structure of a three-dimensional porous aluminum substrate, a zinc-aluminum alloy layer, and a zinc functional layer. The thickness of the zinc-aluminum alloy layer and the zinc functional layer are optimized. The zinc-aluminum alloy layer buffers expansion stress, and the zinc functional layer provides sodium-affinity alloying sites. The zinc-aluminum alloy layer, as a composition gradient transition layer, forms good interfacial compatibility with the aluminum substrate, achieving metallurgical bonding after annealing. Furthermore, it absorbs the volume expansion stress generated by zinc-sodium alloying through its own plastic deformation, avoiding stress concentration that could lead to coating peeling.

[0018] The aluminum current collector for a negative electrode-free sodium battery provided by this invention has the following advantages: it can effectively solve the problem of cyclic peeling failure of magnetron sputtered metal coatings and significantly improve the interfacial bonding force between the zinc layer and porous aluminum; it can achieve metallurgical bonding and mechanical interlocking between the zinc layer and the aluminum substrate, and adapt to the repeated expansion and contraction of zinc-sodium alloy; it can maintain the three-dimensional porous structure without clogging, and improve the cycle stability and sodium affinity of the negative electrode-free sodium battery. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the porous current collector preparation process. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0022] To address the problem of metal coating expansion and peeling in existing aluminum current collectors for negative electrode-free sodium batteries, this invention optimizes the structure of the aluminum current collector for negative electrode-free sodium batteries. The current collector structure consists of a three-dimensional porous aluminum substrate and a double-layer gradient coating layer. The optimized structure can effectively solve the problem of metal coating expansion and peeling.

[0023] This invention provides an aluminum current collector for a negative electrode-free sodium battery, comprising a three-dimensional porous aluminum substrate, on which a zinc-aluminum alloy layer and a zinc functional layer are sequentially deposited. The zinc-aluminum alloy layer can buffer expansion stress, and the zinc functional layer provides sodium-affinity alloying sites, which can significantly improve the interfacial bonding force between the zinc layer and the porous aluminum, and solve the problem of cyclic peeling failure of the magnetron sputtered zinc layer; it can achieve metallurgical bonding and mechanical interlocking between the zinc layer and the aluminum substrate, and is adapted to the repeated expansion and contraction of the zinc-sodium alloy.

[0024] The thickness of the zinc-aluminum alloy layer is 10nm to 50nm, such as 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, etc., preferably 20nm to 40nm. The thickness of the zinc functional layer is 50nm to 500nm, such as 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc., preferably 100nm to 300nm.

[0025] In some embodiments, the molar ratio of zinc to aluminum in the zinc-aluminum alloy layer is 1:(0.3~1.2), such as 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, etc. By adjusting the molar ratio of zinc to aluminum, expansion stress can be better buffered, and the interfacial bonding force between the zinc layer and porous aluminum can be improved. If the aluminum content is too low, the interfacial compatibility between the transition layer and the aluminum substrate is weak, the metallurgical bonding effect is poor, and the stress buffering capacity is insufficient; if the aluminum content is too high, the sodium affinity of the transition layer decreases, which will increase the overall sodium nucleation overpotential and weaken the sodium affinity modification effect.

[0026] In some embodiments, the thickness of the three-dimensional porous aluminum substrate is 20 μm to 40 μm, such as 20 μm, 23 μm, 25 μm, 28 μm, 30 μm, 33 μm, 35 μm, 38 μm, 40 μm, etc.; the pore size is 1 μm to 5 μm, such as 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, etc.; and the porosity is 70% to 90%, such as 70%, 73%, 75%, 78%, 80%, 83%, 85%, 88%, 90%, etc. By optimizing the pore size and porosity of the three-dimensional porous aluminum substrate, the three-dimensional porous structure is better kept from clogging, improving the cycle stability and sodium affinity long-term performance of the anode-free sodium battery.

[0027] Tests have shown that the interfacial bonding force of the aluminum current collector for sodium-free batteries provided in this embodiment of the invention is significantly improved; the sodium affinity effect is stable and long-lasting, and the sodium nucleation overpotential is reduced by more than 30%; the coating is ultra-thin and does not clog pores, and the three-dimensional porous structure is completely preserved.

[0028] This invention also provides a method for preparing an aluminum current collector for a negative electrode-free sodium battery, comprising sequentially depositing a zinc-aluminum alloy layer and a zinc functional layer on a three-dimensional porous aluminum substrate to form a structure of a three-dimensional porous aluminum substrate + a double-layer gradient coating layer, achieving metallurgical bonding and mechanical interlocking between the zinc layer and the aluminum substrate, better adapting to the repeated expansion and contraction of the zinc-sodium alloy, and solving the problem of cyclic peeling failure of the magnetron sputtered zinc layer. Figure 1 As shown, the specific steps are as follows: S1, Pretreatment and Plasma Etching Before depositing the zinc-aluminum alloy layer and the zinc functional layer, the three-dimensional porous aluminum substrate is pretreated and plasma etched. The pretreatment achieves surface cleaning, and the plasma etching forms a nano-interlocking structure on the surface.

[0029] In some embodiments, the pretreatment step includes cleaning and drying the three-dimensional porous aluminum substrate to obtain a clean substrate material. The solvent used for cleaning can be an organic alcohol solvent, such as ethanol or isopropanol. During the plasma etching process, argon plasma etching is used for an etching time of 2 to 5 minutes, such as 2 minutes, 3 minutes, 4 minutes, or 5 minutes. After etching, a nano-interlocking structure is formed on the surface, and the nanostructure is anchored by plasma etching to secure the coating.

[0030] S2, gradient magnetron sputtering A zinc-aluminum alloy layer and a zinc functional layer were deposited using magnetron sputtering. During the magnetron sputtering process, the substrate adopted a planetary revolution mode, and negative bias was used to enhance the coating's wraparound properties. This ensured that the zinc-aluminum alloy layer and the zinc functional layer uniformly coated the outer surface of the porous aluminum framework and the inner walls of the shallow pores, preventing over-deposition and clogging of the pore openings, and fully preserving the mass transfer channels and volume buffering capacity of the three-dimensional porous structure. The background vacuum was controlled at 1×10⁻⁶ during the deposition process. -4 Pa ~5×10 -4 Pa, for example, can be 1×10 - 4 Pa, 2×10 -4 Pa, 3×10 -4 Pa, 4×10 -4 Pa, 5×10 -4 Pa, etc., the background vacuum refers to the ultimate vacuum of the cavity before the sputtering gas is introduced; the working gas pressure is controlled at 0.4Pa~0.7Pa, such as 0.4Pa, 0.5Pa, 0.6Pa, 0.7Pa, etc., and the working gas can be an inert gas such as argon.

[0031] In some embodiments, during the deposition of the zinc-aluminum alloy layer, a Zn-Al alloy target is used, with a sputtering power of 80W~200W, a target-substrate distance of 80mm~120mm, a substrate temperature of 25℃~80℃, and a substrate negative bias of -50V~-150V. By adjusting the process parameters for depositing the zinc-aluminum alloy layer, a uniform zinc-aluminum alloy transition layer is formed to counteract alloy expansion stress.

[0032] In some embodiments, during the deposition of the zinc functional layer, a pure zinc target is used, the sputtering power is 100W~250W, the target-substrate distance is 80mm~120mm, the substrate temperature is 25℃~80℃, and the substrate negative bias voltage is -30V~-100V. By adjusting the process parameters for depositing the zinc functional layer, a uniform zinc functional layer is formed, providing more uniform sodium-affinity alloying sites.

[0033] S3, Low-temperature vacuum annealing After depositing the zinc-aluminum alloy layer and the zinc functional layer, low-temperature vacuum annealing can promote limited interdiffusion of zinc and aluminum atoms at the interface, forming a nanoscale solid solution transition zone with controllable thickness. This transforms physical adhesion into metallurgical bonding, while avoiding deformation of the porous aluminum skeleton and collapse of the pore structure caused by high temperature, further improving the adhesion of the zinc coating.

[0034] In some embodiments, during the low-temperature vacuum annealing process, the vacuum is controlled to be ≤1×10⁻⁶. -3 Pa; annealing temperature is 200℃~400℃, such as 200℃, 230℃, 250℃, 280℃, 300℃, 330℃, 350℃, 380℃, 400℃, etc.; holding time is 30min~60min, such as 30min, 35min, 40min, 45min, 50min, 55min, 60min, etc. By adjusting the parameters of low-temperature annealing, an interfacial solid solution can be formed after low-temperature annealing, thereby improving the adhesion of the coating.

[0035] This invention also provides a sodium-free negative electrode battery, including an aluminum current collector for the sodium-free negative electrode battery provided in this invention, and may further include a positive electrode sheet, a separator, and an electrolyte, assembled into a complete battery.

[0036] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0037] Example 1 This embodiment provides an aluminum current collector for a negative electrode-free sodium battery, and its preparation steps are as follows: (1) Pretreatment and plasma etching Commercially available three-dimensional porous aluminum foil, 30μm thick, with pore size of 1~5μm and porosity of about 80%.

[0038] Pretreatment: The porous aluminum foil is cleaned with ethanol and isopropanol, and then dried.

[0039] Plasma etching: Argon plasma etching is performed with a power of 100W (the same below) and an etching time of 3 minutes to form a nano-concave-convex interlocking structure on the surface.

[0040] (2) Gradient magnetron sputtering: Background vacuum 3×10 -4 Pa, working gas pressure 0.5 Pa; sequentially deposit a zinc-aluminum alloy layer with a thickness of 30 nm and a zinc functional layer with a thickness of 200 nm.

[0041] Zinc-aluminum alloy layer: Zn-Al alloy target material (molar ratio of zinc to aluminum is 1:0.8), sputtering power is 150 W, target-substrate distance is 100 mm, substrate temperature is 50℃, and substrate negative bias voltage is -100 V.

[0042] Deposited zinc functional layer: Pure zinc target material is used, sputtering power is 200W, target-substrate distance is 100mm, substrate temperature is 50℃, and substrate negative bias voltage is -60V.

[0043] (3) Low-temperature vacuum annealing Control vacuum ≤1×10 -3 Pa was kept at 300℃ for 45 minutes.

[0044] Example 2 The only difference from Example 1 is that the thickness of the zinc-aluminum alloy layer is 20 nm and the thickness of the zinc functional layer is 100 nm.

[0045] Example 3 The only difference from Example 1 is that the thickness of the zinc-aluminum alloy layer is 40 nm and the thickness of the zinc functional layer is 300 nm.

[0046] Example 4 The only difference from Example 1 is that the thickness of the zinc-aluminum alloy layer is 10 nm and the thickness of the zinc functional layer is 50 nm.

[0047] Example 5 The only difference from Example 1 is that the thickness of the zinc-aluminum alloy layer is 50 nm and the thickness of the zinc functional layer is 500 nm.

[0048] Example 6 The only difference from Example 1 is that the molar ratio of zinc to aluminum in the Zn-Al alloy target in step (2) is 1:0.3.

[0049] Example 7 The only difference from Example 1 is that the molar ratio of zinc to aluminum in the Zn-Al alloy target in step (2) is 1:0.6.

[0050] Example 8 The only difference from Example 1 is that the molar ratio of zinc to aluminum in the Zn-Al alloy target in step (2) is 1:0.1.

[0051] Example 9 The only difference from Example 1 is that the molar ratio of zinc to aluminum in the Zn-Al alloy target in step (2) is 1:1.5.

[0052] Example 10 The only difference from Example 1 is that the annealing temperature in step (3) is 200°C.

[0053] Example 11 The only difference from Example 1 is that the annealing temperature in step (3) is 400°C.

[0054] Example 12 The only difference from Example 1 is that the annealing temperature in step (3) is 150°C.

[0055] Example 13 The only difference from Example 1 is that the annealing temperature in step (3) is 500°C.

[0056] Example 14 The only difference from Example 1 is that the argon plasma etching step is not performed, and the coating is deposited directly.

[0057] Comparative Example 1 The only difference from Example 1 is that step (2) deposits only the zinc functional layer, with a thickness equal to the sum of the thicknesses of the zinc-aluminum alloy layer and the zinc functional layer in Example 1.

[0058] Comparative Example 2 The only difference from Example 1 is that the thickness of the zinc-aluminum alloy layer is 5nm and the thickness of the zinc functional layer is 30nm.

[0059] Comparative Example 3 The only difference from Example 1 is that the thickness of the zinc-aluminum alloy layer is 70 nm and the thickness of the zinc functional layer is 600 nm.

[0060] Comparative Example 4 The only difference from Example 1 is that a single-layer zinc coating is prepared by electroplating, with a total thickness of 230 nm, which is the same as the total coating thickness in Example 1, and there is no zinc-aluminum alloy transition layer.

[0061] Experimental Example 1 The performance of the aluminum current collectors for sodium-free batteries prepared in the test examples and comparative examples is shown in Table 1.

[0062] Test method: (1) Coating interface adhesion: The 90° peel test was used, referring to GB / T 2792-2014 standard, using 3M 610 test tape, with a peel rate of 300 mm / min; (2) Sodium nucleation overpotential: The current collector was used as the working electrode, a sodium metal sheet as the counter electrode, a 1M NaPF6DEGDME solution was used as the electrolyte, a PE membrane was used, and the test environment temperature was 25℃. A CR2032 coin cell was assembled, and the overpotential was measured at 0.1 mA / cm². 2 Deposition at current density of 1mAh / cm 2 Sodium nucleation overpotential is the difference between the peak nucleation potential and the stable deposition potential. The sodium nucleation overpotential of a conventional blank three-dimensional porous aluminum current collector is about 110 mV.

[0063] (3) Cyclic capacity retention: Assemble a sodium-free full cell (with Prussian blue analogue as the positive electrode), cycle 100 times at 0.5C, and calculate the capacity retention.

[0064] Table 1. Performance of aluminum current collectors for negative electrode-free sodium batteries prepared in the examples and comparative examples.

[0065] As can be seen from Table 1, the overall performance of the double-layer gradient structure of the present invention is significantly better than that of the prior art: compared with Comparative Example 1 (single-layer pure zinc coating) and Comparative Example 4 (electroplated single-layer zinc), the present invention introduces a zinc-aluminum alloy transition layer, which increases the coating peel strength by more than 2 times and the cycle capacity retention rate by more than 15 percentage points, effectively solving the core problem of zinc coating peeling due to cyclic expansion.

[0066] Comparing Example 1 and Example 14, the interfacial bonding strength decreased significantly and the cycle life decreased significantly when there was no plasma etching. Comparing Example 1 and Example 12, when the annealing temperature was insufficient, the atomic interdiffusion was insufficient, the metallurgical bonding effect was weak, and the bonding strength was only slightly improved. This verifies that mechanical interlocking and metallurgical bonding effectively improve the bonding strength between coatings, and also illustrates the role of plasma etching and low-temperature annealing.

[0067] The comparison of the examples and comparative examples shows that the material exhibits optimal overall performance when the zinc-aluminum alloy layer thickness is 10-50 nm, the zinc functional layer thickness is 50-500 nm, the zinc-aluminum molar ratio is 0.3-1.2, and the annealing temperature is 200-400℃. Performance degradation occurs to varying degrees when the above ranges are exceeded, as detailed below: Compared with Example 1 and Comparative Examples 2-3, if the transition layer is too thin, the stress buffering and bonding strength improvement effect is limited, and the coating is easy to separate and peel off during cycling; if the transition layer is too thick, the total coating thickness will increase, which will also lead to smaller pores, increased ion transport resistance, loss of the advantages of three-dimensional porous structure, and decreased cycling performance. Comparing Examples 1 and 6-9, if the aluminum content in the intermediate coating is too low, the adhesion will not be sufficiently improved; if the aluminum content is too high, the sodium affinity will decrease and the nucleation overpotential will increase. Comparing Examples 1 and 10-13, if the annealing temperature is too low, an effective metallurgical bond cannot be formed; if the annealing temperature is too high, the porous aluminum skeleton is prone to thermal deformation, the pore structure shrinks, and the cycle performance deteriorates.

[0068] Tests showed that the sodium nucleation overpotential of the blank three-dimensional porous aluminum current collector was about 110mV. Compared with the pure aluminum current collector, the zinc functional layer can reduce the sodium nucleation overpotential by nearly half, effectively guiding uniform sodium deposition and inhibiting the formation of dendrites and dead sodium.

[0069] In summary, this invention achieves mechanical locking between the coating and the porous aluminum substrate through plasma etching, further strengthens the coating adhesion through stress buffering of the zinc-aluminum alloy transition layer and metallurgical combination of low-temperature annealing, and enhances the sodium affinity of the zinc layer, thus solving the two core problems of coating peeling and poor sodium affinity in aluminum current collectors without negative electrodes, effectively improving the cycle stability and lifespan of the battery.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An aluminum current collector for a negative electrode-free sodium battery, characterized in that, Includes a three-dimensional porous aluminum substrate, on which a zinc-aluminum alloy layer and a zinc functional layer are sequentially deposited; The thickness of the zinc-aluminum alloy layer is 10nm~50nm, and the thickness of the zinc functional layer is 50nm~500nm.

2. The aluminum current collector for a negative electrode-free sodium battery according to claim 1, characterized in that, The thickness of the zinc-aluminum alloy layer is preferably 20nm~40nm, and the thickness of the zinc functional layer is preferably 100nm~300nm; And / or, the molar ratio of zinc to aluminum in the zinc-aluminum alloy layer is 1:(0.3~1.2).

3. The aluminum current collector for a negative electrodeless sodium battery according to claim 1 or 2, characterized in that, The thickness of the three-dimensional porous aluminum substrate is 20μm~40μm, the pore size is 1μm~5μm, and the porosity is 70%~90%.

4. A method for preparing an aluminum current collector for a negative electrode-free sodium battery according to any one of claims 1-3, characterized in that, include: The zinc-aluminum alloy layer and the zinc functional layer are sequentially deposited on the three-dimensional porous aluminum substrate.

5. The preparation method according to claim 4, characterized in that, The zinc-aluminum alloy layer and the zinc functional layer are deposited by magnetron sputtering, and the base vacuum is controlled to be 1x10 -4 Pa during the deposition process -4 Pa, and the working pressure is 0.4 Pa~0.7 Pa.

6. The preparation method according to claim 5, characterized in that, During the deposition of the zinc-aluminum alloy layer, a Zn-Al alloy target is used, the sputtering power is 80W~200W, the target-substrate distance is 80mm~120mm, the substrate temperature is 25℃~80℃, and the substrate negative bias voltage is -50V~-150V.

7. The preparation method according to claim 5, characterized in that, During the deposition of the zinc functional layer, a pure zinc target is used, the sputtering power is 100W~250W, the target-substrate distance is 80mm~120mm, the substrate temperature is 25℃~80℃, and the substrate negative bias voltage is -30V~-100V.

8. The preparation method according to claim 4, characterized in that, After depositing the zinc-aluminum alloy layer and the zinc functional layer, low-temperature vacuum annealing is performed, with the vacuum controlled to be ≤1×10⁻⁶. -3 Pa, annealing temperature is 200℃~400℃, holding time is 30min~60min.

9. The preparation method according to claim 4, characterized in that, Before depositing the zinc-aluminum alloy layer and the zinc functional layer, the three-dimensional porous aluminum substrate is pretreated and plasma etched. The pretreatment step includes: cleaning and drying the three-dimensional porous aluminum substrate; the solvent used for cleaning is an organic alcohol solvent; During the plasma etching process, argon plasma etching is used, and the etching time is 2 min to 5 min.

10. A sodium battery without a negative electrode, characterized in that, Includes the aluminum current collector for a sodium-free battery as described in any one of claims 1-3 or the aluminum current collector for a sodium-free battery prepared by the preparation method described in any one of claims 4-9.

Images