Thin film all-solid-state battery and preparation method thereof

Abstract

The invention provides a thin-film all-solid-state battery and a preparation method thereof, and belongs to the technical field of solid-state batteries, the thin-film all-solid-state battery is characterized in that a positive electrode current collector layer is used as a positive electrode substrate, a positive electrode layer, a solid electrolyte layer, a negative electrode layer and a negative electrode current collector layer are sequentially deposited by adopting a vacuum coating technology, and target raw materials of the positive electrode layer comprise a conductive metal source and a sulfur source; the sulfur source is a sulfur-containing electrode material, the sulfur-containing electrode material comprises elemental sulfur and one of compounds simultaneously containing the elemental sulfur and metal elements, and the conductive metal source is a copper source. According to the thin-film all-solid-state battery and the preparation method thereof provided by the invention, the sulfur element is applied to the thin-film all-solid-state battery, so that the purposes of low cost, simple and convenient process, convenience in mass production and high battery performance are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state batteries, and in particular to a thin-film all-solid-state battery and a preparation method thereof. Background Art

[0002] In today's global context of sustainable development, innovation in energy storage technology has become a key driver of progress across various sectors. As the core of energy storage, every major breakthrough in battery technology has the potential to revolutionize the industry. All-solid-state batteries, representing a new generation of battery technology, are gradually emerging and are poised to revolutionize the existing energy landscape. These batteries, which replace the electrolyte and separator in traditional lithium-ion batteries with solid electrolytes, have attracted widespread attention for their superior safety and wide temperature range adaptability.

[0003] Room-temperature liquid sodium-sulfur (RT Na-S) batteries have been investigated as promising energy storage systems due to their high theoretical energy density, low cost, and the abundance of sodium and sulfur. However, the inherent electronic insulation of sulfur, the dissolution and shuttling of intermediate sodium polysulfides, and, in particular, the sluggish conversion kinetics, have limited the commercial application of liquid RT Na-S batteries. Furthermore, the volatility of sulfur-containing raw materials in high vacuum and their inherently sluggish kinetics have hindered researchers' empirical integration into thin-film all-solid-state batteries.

[0004] In addition, patent publication number CN119481230A, entitled "A All-Solid-State Thin Film Battery and Its Preparation Method," discloses a new all-solid-state thin film battery prepared using a vacuum coating method using Na2S or S as a cathode target. However, Na2S or S are electronic insulating materials. To ensure that Na2S particles or S particles can smoothly release or receive electrons to achieve the charge and discharge process, in certain specific circumstances, when using a Na2S target or S target for coating, a carbon target also needs to be used for simultaneous coating to generate Na2S / C or S / C composite coated particles, thereby improving the charge and discharge efficiency of the cathode material. However, this dual-target simultaneous coating scenario not only greatly increases the coating process difficulty, but also makes it difficult to control the weight ratio of the various components in the Na2S / C composite film or S / C composite film, resulting in uneven coating and poor battery performance. Summary of the Invention

[0005] In light of this, the present invention provides a thin-film all-solid-state battery and its preparation method. A target material is formed by mixing sulfur source powder and metal powder. This vacuum coating not only facilitates the formation of a sulfur-containing composite thin film with sufficient conductivity, but also allows the metal in the composite film to react with sulfur to form metal sulfide during the charge and discharge phases. This metal component then catalyzes the charge and discharge process, improving charge and discharge efficiency. This target material and coating process, when applied to thin-film all-solid-state batteries, achieves low cost, a simple process, ease of mass production, and high battery performance.

[0006] To achieve the above objectives, the present invention provides a thin-film all-solid-state battery cathode substrate target material, wherein the target material raw materials include a conductive metal source and a sulfur source, and the sulfur source is a sulfur-containing electrode material.

[0007] Optionally, the conductive metal source is one or a combination of two or more of a copper source, an iron source, an aluminum source, and a zinc source.

[0008] Optionally, the copper source is copper element, and the copper element is powder with a particle size D50 between 50nm and 50um.

[0009] Optionally, the sulfur source includes one or a combination of sulfur and a compound containing both sulfur and a metal element.

[0010] Optionally, the compound containing both sulfur and metal elements is one or a combination of two or more of sodium sulfide, lithium sulfide, iron sulfide, zinc sulfide, and copper sulfide; and the sodium sulfide is one or a combination of two of sodium disulfide and sodium polysulfide.

[0011] In order to achieve the above-mentioned purpose, the present invention also provides a method for preparing a positive electrode base target material for a thin-film all-solid-state battery, which is characterized in that it includes the following steps: mixing a copper source and a sulfur source, pressing them after mechanical grinding, and sintering them by vacuum hot pressing to obtain a positive electrode base target material.

[0012] Optionally, the mass percentage of the sulfur source is 60wt%-95wt%, and the mass percentage of the copper source is 5wt%-40wt%.

[0013] Optionally, the mechanical grinding is ball milling, sand milling or vibration milling.

[0014] Optionally, the vacuum hot pressing method is performed at a temperature of 150° C. to 700° C. and a pressure of 20 MPa to 400 MPa.

[0015] In order to achieve the above-mentioned purpose, the present invention also provides a method for preparing a thin-film all-solid-state battery, comprising the following steps: using the positive electrode collector layer as the positive electrode substrate, and using vacuum coating technology to sequentially deposit the positive electrode layer, solid electrolyte layer, negative electrode layer and negative electrode collector layer, wherein the target material of the positive electrode layer is the positive electrode substrate target material of the thin-film all-solid-state battery.

[0016] Optionally, the thickness of the positive electrode current collector layer is 10nm-1000μm; the thickness of the positive electrode layer is 10nm-50μm; the thickness of the solid electrolyte layer is 10nm-50μm; the thickness of the negative electrode layer is 10nm-50μm; the thickness of the negative electrode current collector layer is 0nm-1000μm.

[0017] Optionally, the thickness of the positive electrode current collector layer is any one of 10 nm, 100 nm, 1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, and 1 mm.

[0018] Optionally, the thickness of the positive electrode layer is any one of 10 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 5 μm, 10 μm, and 50 μm.

[0019] Optionally, the thickness of the solid electrolyte layer is any one of 10 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 5 μm, 10 μm, and 50 μm.

[0020] Optionally, the thickness of the negative electrode layer is any one of 10 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 5 μm, 10 μm, and 50 μm.

[0021] Optionally, the thickness of the negative electrode current collector layer is any one of 0 nm, 10 nm, 100 nm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, and 1 mm.

[0022] Optionally, the vacuum coating technology is one or a combination of vacuum evaporation coating and magnetron sputtering coating.

[0023] Optionally, the material of the positive electrode current collector layer is one or a combination of two or more of copper foil, aluminum foil, stainless steel foil, composite copper foil, composite aluminum foil, metal film formed by plating, composite conductive film, etc.; the target material of the solid electrolyte layer is sodium phosphate, Na3La(PO4)2, Na-β-Al2O3, Na 1+x Zr2Six P 3-x O 12 One or a combination of two or more types of sodium superion conductors.

[0024] Optionally, the target material of the negative electrode layer is one or a combination of two or more of tin, sodium-tin alloy, carbon sodium storage material, and composite materials containing sodium storage functional materials; the target material of the negative electrode current collector layer is one or a combination of two or more of sodium, tin, sodium-tin alloy, copper, and aluminum.

[0025] In order to achieve the above-mentioned purpose, the present invention also provides a thin-film all-solid-state battery prepared by a method for preparing a thin-film all-solid-state battery.

[0026] The above technical solution of the present invention includes at least the following beneficial effects: The present application adopts a special positive electrode base target material combined with a preparation method to obtain a positive electrode base target material, and the positive electrode base target material combined with the battery preparation method achieves the purpose of not requiring annealing, facilitating mass production, and having high battery performance. The battery obtained in the present application has a high energy density, which can exceed 500Wh / kg; the battery provided by the present application has a high rate performance, which can exceed 10C; the battery provided by the present application has a long life, which is greater than 10,000 cycles; the battery material provided by the present application is cheap and low in cost, as low as 0.2 yuan / Wh; the battery provided by the present application is safe and completely non-flammable; the battery provided by the present application has excellent high and low temperature resistance and can be used under conditions of -40℃~80℃; the battery manufacturing process provided by the present application is simple and can be completed within 2 days; the battery provided by the present application can be internally connected in series and parallel, can withstand large current and high voltage, and directly form a pack across the module without the need for cumbersome components such as a condensation water explosion-proof system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the cross-sectional structure of the thin-film all-solid-state battery in Example 1 of the present invention; Figure 2 This is a physical picture of the thin-film all-solid-state battery in Example 1 of the present invention; Figure 3 This is a surface scanning electron microscope image of the thin-film all-solid-state battery in Example 1 of the present invention; Figure 4 Surface element distribution test results of the thin-film all-solid-state battery in Example 1 of the present invention; Figure 5 This is the charge and discharge curve of the second cycle of the thin-film all-solid-state battery in Example 1. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0029] Example 1 A thin-film all-solid-state battery, including a target material for the cathode layer, is a thin-film all-solid-state battery substrate target. The production process for the thin-film all-solid-state battery substrate target comprises the following steps: mixing sodium sulfide powder and copper powder, sand-milling them until uniform, then pressing them, and sintering them using vacuum hot pressing. The mass percentage of sodium sulfide (anhydrous, produced by Rizhao Yijie Xinyuan New Materials Co., Ltd., hereinafter the same) is 60wt%, and the mass percentage of copper powder (produced by Guangdong Xiaoda Chemical Co., Ltd., with a particle size D50 of 30nm, hereinafter the same) is 40wt%. The vacuum hot pressing conditions are a temperature of 500°C and a pressure of 300MPa. The resulting composite target material is 60Na2S+40Cu (diameter 50×3mm).

[0030] The positive electrode current collector layer is made of copper foil (20μm thick); the solid electrolyte layer target is Na₃PO₄ (φ50×3mm, purchased from Yipinchuancheng (Beijing) Technology Co., Ltd.); and the negative electrode layer target is made of tin (φ50×3mm, purchased from Yipinchuancheng (Beijing) Technology Co., Ltd.). The positive electrode current collector layer is 20μm thick, and the positive electrode layer is designed to be 400nm thick; the solid electrolyte layer is designed to be 200nm thick, and the negative electrode layer is designed to be 50nm thick. The positive electrode, solid electrolyte, and negative electrode thin film layers are deposited using vacuum magnetron sputtering.

[0031] A production process for a thin-film all-solid-state battery comprises the following steps: using a positive electrode current collector layer as a positive electrode substrate, sequentially depositing a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector layer using vacuum coating technology; Step 1: Use a three-target magnetron sputtering device (model VTC-600-3HD) manufactured by Shenyang Kejing Automation Equipment Co., Ltd. Install the 60Na2S+40Cu composite cathode target, Na3PO4 target, and Sn target prepared above on the three target heads, respectively. Place a copper foil (100 mm diameter, 20 μm thickness) on the sample stage as a thin film deposition substrate, and set up a mask mold to prepare a sandwich structure with a positive electrode layer / solid electrolyte layer / negative electrode layer without short circuits. Set the sample stage to rotate at 10 rpm and evacuate to 1.0×10 -3 After the pressure drops below 4 Pa, adjust the device, introduce argon at a flow rate of 12 ml / min, and control the vacuum value at around 4 Pa.

[0032] Step 2: Slowly adjust the RF power of the thin-film all-solid-state battery substrate target to 100W. When the film thickness meter shows a thickness change rate of 0.1nm / s, open the sample stage shutter to allow the sputtered sodium sulfide and copper to deposit on the copper foil on the sample stage. When the cumulative deposition thickness reaches 400nm, close the sample stage shutter and reduce the RF power of the thin-film all-solid-state battery substrate target to zero. At this point, the positive electrode layer is formed.

[0033] Step 3: While maintaining a vacuum of approximately 4 Pa, introduce nitrogen at a flow rate of 12 ml / min. Slowly adjust the RF power of the sodium phosphate target to 100 W. When the film thickness meter displays a thickness change rate of 0.1 nm / s, open the sample stage shutter to allow the sputtered sodium phosphate to continue depositing on the copper foil on the sample stage. When the cumulative deposition thickness reaches 200 nm, close the sample stage shutter and reduce the RF power of the sodium phosphate target to zero. At this point, a solid electrolyte layer covering the positive electrode layer is formed.

[0034] Step 4: Turn off the nitrogen. Slowly adjust the RF power of the tin target to 50W. When the film thickness meter shows a rate of change of 0.1nm / s, open the sample stage shutter to allow the sputtered tin to continue depositing on the copper foil on the sample stage. When the cumulative deposition thickness reaches 50nm, close the sample stage shutter and reduce the RF power of the tin target to zero. At this point, the negative electrode layer is formed above the solid electrolyte layer.

[0035] Step 5: Cut the vacuum-coated copper foil.

[0036] Copper foil is used as the positive electrode current collector layer to lead out the positive electrode tab, and tin layer is used as the negative electrode current collector layer to lead out the negative electrode tab. A small aluminum-plastic film soft-pack battery, i.e., a thin-film all-solid-state battery, is manufactured in a glove box with an argon atmosphere (water content less than 0.1ppm, oxygen content less than 0.1ppm).

[0037] Performance testing: The film thickness is measured using the aforementioned coating equipment's film thickness meter, and the weights of sodium sulfide, sodium phosphate, and tin in the thin-film battery are calculated theoretically. When calculating charge and discharge capacity, Na2S or S is used as the weight of the active charge and discharge material. Energy density is calculated by dividing the battery energy by the deposited weight of all coating materials (positive electrode layer + electrolyte layer + negative electrode layer).

[0038] Use a battery charge and discharge system (SLAN-CT2001A battery tester) to perform charge and discharge tests on small soft-pack batteries.

[0039] The first cycle charging current is 1uA, and the discharge current is 1uA. The test results show that the battery has a first cycle charging capacity of 528mAh / g, a discharge capacity of 491mAh / g, and a coulombic efficiency of 93%.

[0040] The second cycle has a charge current of 1uA and a discharge current of 1uA. The second cycle has a charge capacity of 515mAh / g, a discharge capacity of 499mAh / g, and a Coulombic efficiency of 97%.

[0041] The third cycle has a charge current of 1uA and a discharge current of 5uA. The charge capacity of the third cycle is 466mAh / g, the discharge capacity is 457mAh / g, and the coulombic efficiency is 98%.

[0042] The fourth cycle has a charge current of 1uA and a discharge current of 1uA. The fourth cycle has a charge capacity of 480mAh / g, a discharge capacity of 475mAh / g, and a coulombic efficiency of 99%.

[0043] After 100 cycles of repeated discharge under the same charge and discharge conditions, the 103rd cycle capacity was 446 mAh / g, the discharge capacity was 441 mAh / g, and the coulombic efficiency was 99%.

[0044] Compared with the discharge capacity of the second cycle, the discharge capacity retention rate of the third cycle is 92%, indicating that the discharge rate performance is good after the discharge current is increased by 5 times.

[0045] The discharge capacity at the 103rd cycle was compared with the discharge capacity at the 4th cycle, and the discharge capacity retention rate was 93%, indicating that the cycle performance was good after 100 cycles of charge and discharge.

[0046] Using the weight of the deposited material in the battery, the discharge capacity of the second cycle, and the average discharge voltage, the energy density of the battery was calculated to be 413Wh / kg.

[0047] Example 2 Compared with Example 1, the only difference is that the mass percentage of Na2S in the composite cathode target is 80wt%, and the mass percentage of copper powder is 20wt%. The vacuum hot pressing conditions are 500°C and 200MPa, resulting in an 80Na2S + 20Cu composite target. In addition, the thickness of the Sn negative electrode thin film layer is adjusted to 70nm to balance the N / P ratio (the ratio of the theoretical capacity of the negative electrode to the theoretical capacity of the positive electrode). The remaining steps and operations are consistent with Example 1.

[0048] Example 3 Compared with Example 1, the only difference is that the mass percentage of Na2S in the composite cathode target is 95wt%, and the mass percentage of copper powder is 5wt%. The vacuum hot pressing conditions are 400°C and 400MPa, resulting in a 95%Na2S + 5%Cu composite target. In addition, the thickness of the Sn negative electrode thin film layer is adjusted to 80nm to balance the N / P ratio (the ratio of the theoretical capacity of the negative electrode to the theoretical capacity of the positive electrode). The remaining steps and operating conditions are the same as those in Example 1.

[0049] Example 4 Compared with Example 1, the only difference is that the raw materials in the composite cathode target are elemental sulfur (purchased from Guangdong Xiaoda Chemical Co., Ltd.) and copper powder (purchased from Guangdong Xiaoda Chemical Co., Ltd.), with the mass percentage of S being 75wt% and the mass percentage of copper powder being 25wt%. The vacuum hot pressing conditions are a temperature of 100°C and a pressure of 50MPa, resulting in a 75S+25Cu composite cathode target. In addition, a NaSn alloy is used as the composite anode target (purchased from Yipinchuancheng (Beijing) Technology Co., Ltd.). The designed thickness of the cathode thin film layer is 800nm, and the designed thickness of the anode thin film layer is adjusted to 300nm to balance the N / P ratio. Other steps and operating conditions are consistent with Example 1.

[0050] Comparative Example 1 Compared with Example 1, the only difference is that the mass percentage of Na2S in the composite cathode target is 100wt%, and the mass percentage of copper powder is 0wt%. The vacuum hot pressing conditions are 500°C and 400MPa, resulting in a 100Na2S+0Cu composite target. To balance the N / P ratio, the designed thickness of the negative electrode thin film layer is adjusted to 90nm. The remaining steps and operating conditions are consistent with Example 1.

[0051] Comparative Example 2 Compared to Example 1, the only difference is that the positive electrode thin film layer is produced by simultaneous coating with two targets: a sodium sulfide target (100 Na2S + 0 Cu, produced in Comparative Example 1) and a copper target (100 Cu, φ50×3 mm, purchased from Yipinchuancheng (Beijing) Technology Co., Ltd.). In step 2 of Comparative Example 1 (i.e., step 2 of Example 1), the RF power of the sodium sulfide target and the copper target is simultaneously adjusted to 100 W for coating to form the positive electrode thin film layer. The ratio of sodium sulfide to copper targets is 1:1. The remaining steps and operating conditions are the same as those in Comparative Example 1.

[0052] The batteries obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to cycle performance tests and rate performance tests. The results are shown in Table 1.

[0053] Table 1 Battery performance test results of Examples 1 to 4 and Comparative Examples 1 to 2

[0054] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A thin film all-solid-state battery cathode substrate target material, characterized in that: The target material raw material includes a conductive metal source and a sulfur source, and the sulfur source is a sulfur-containing electrode material.

2. The thin-film all-solid-state battery cathode substrate target according to claim 1, characterized in that: The conductive metal source is one of copper source, iron source, aluminum source and zinc source, or a combination of two or more thereof.

3. The thin-film all-solid-state battery cathode substrate target according to claim 2, characterized in that: The copper source is copper element, and the copper element is powder, and its particle size D50 is between 50nm and 50um.

4. The thin-film all-solid-state battery cathode substrate target according to claim 1, characterized in that: The sulfur-containing electrode material includes one or a combination of sulfur and a compound containing sulfur and a metal element.

5. A method for preparing a thin-film all-solid-state battery cathode substrate target material according to claim 1, characterized in that: The method comprises the following steps: mixing a copper source and a sulfur source, grinding them mechanically to make them uniform and then pressing them, and sintering them into a shape by vacuum hot pressing to obtain a positive electrode base target material.

6. The method for preparing a thin film all-solid-state battery cathode substrate target material according to claim 5, characterized in that: The mass percentage of the sulfur source is 60wt%-95wt%, and the mass percentage of the copper source is 5wt%-40wt%.

7. The method for preparing a thin-film all-solid-state battery cathode substrate target material according to claim 5, characterized in that: The conditions of the vacuum hot pressing method are a temperature of 150° C. to 700° C. and a pressure of 20 MPa to 400 MPa.

8. A method for preparing a thin film all-solid-state battery, characterized in that: The method comprises the following steps: using the positive electrode current collector layer as the positive electrode substrate, sequentially depositing the positive electrode layer, the solid electrolyte layer, the negative electrode layer and the negative electrode current collector layer by vacuum coating technology, wherein the target material of the positive electrode layer is the thin film all-solid-state battery positive electrode substrate target material as described in claims 1 to 3.

9. The method for preparing a thin-film all-solid-state battery according to claim 8, characterized in that: The material of the positive electrode current collector layer is one or a combination of two or more of copper foil, aluminum foil, stainless steel foil, composite copper foil, composite aluminum foil, metal film formed by plating, composite conductive film, etc.; the target material of the solid electrolyte layer is sodium phosphate, Na3La(PO4)2, Na-β-Al2O3, Na 1+x Zr2Si x P 3-x O 12 One or a combination of two or more types of sodium superion conductors.

10. A thin-film all-solid-state battery prepared by the method for preparing a thin-film all-solid-state battery according to any one of claims 8 to 9.

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