Composite thin film cathode material for all-solid-state thin film battery and preparation method and application thereof

Abstract

The application discloses a composite thin film positive electrode material for all-solid-state thin film batteries and a preparation method and application thereof. The composite thin film positive electrode material comprises a substrate and a composite thin film covering the surface of the substrate. The composite thin film is composed of V2O5 and Ag2O. The mass ratio of V2O5 to Ag2O in the composite thin film is 1: (5.37-9.56). The application utilizes amorphous V2O5 to modify Ag2O, and prepares a composite thin film positive electrode with high capacity without annealing. The composite thin film positive electrode is deposited on various substrates through magnetron co-sputtering, and the deposited thin film is dense and uniform. The application does not need any annealing treatment, and can be compatible with various heat-sensitive materials and devices.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage materials and devices, specifically to a composite thin-film cathode material for all-solid-state thin-film batteries, its preparation method, and its application. Background Technology

[0002] With the rapid development of microelectronic systems such as the Internet of Things, wearable electronics, and micro sensors, there is an urgent need for high-performance, high-safety, and integrable micro energy storage devices. All-solid-state thin-film batteries are considered an ideal micro-power solution due to their advantages such as the absence of liquid electrolytes, high safety, and ease of integration. However, existing thin-film cathode materials generally suffer from low specific capacity, require high-temperature annealing (>500 °C) for crystallization, and are incompatible with microfabrication processes, severely restricting their practical applications. The high-temperature annealing process not only limits the use of flexible or temperature-sensitive substrates but also increases process complexity and energy consumption, making it difficult to be compatible with low-temperature microfabrication processes such as silicon-based integrated circuits. Meanwhile, most traditional thin-film cathode materials (such as LiCoO2) have limited specific capacity, failing to meet the ever-increasing demand for high energy density and limiting device miniaturization and long-term operation.

[0003] Therefore, developing a high-capacity thin-film cathode that can be directly fabricated at low temperatures or room temperature without high-temperature annealing has become crucial for the practical application of all-solid-state thin-film batteries. Such materials should possess high ionic conductivity, good interfacial stability, and scalable deposition characteristics, thereby achieving true deep integration with modern microelectronic processes and providing reliable and efficient micro-energy support for next-generation microelectronic devices. Summary of the Invention

[0004] This invention addresses the problem of poor cycle stability of pure Ag₂O cathode materials, which are typically only used in primary batteries. It provides a composite thin-film cathode material for all-solid-state thin-film batteries, its preparation method, and its applications. The cathode material of this invention is a composite thin-film cathode based on the nano-confining effect of amorphous V₂O₅. Through the confinement effect of amorphous V₂O₅, this invention effectively suppresses the agglomeration of crystalline Ag₂O particles during cycling, preventing structural degradation and thus significantly improving the structural and cycle stability of the Ag₂O cathode. The resulting composite thin-film cathode requires no annealing treatment, possesses high capacity characteristics, and can provide reliable and efficient micro-energy support for next-generation microelectronic devices.

[0005] To achieve the above objectives, the technical solution designed by the present invention is as follows:

[0006] This invention provides a composite thin-film cathode material for all-solid-state thin-film batteries. The composite thin-film cathode material includes a substrate and a composite thin film covering the surface of the substrate. The composite thin film is composed of V2O5 and Ag2O, and the mass ratio of V2O5 to Ag2O in the composite thin film is 1:(5.37-9.56).

[0007] Furthermore, the thickness of the composite film is 300-2000 nm.

[0008] Furthermore, in the composite film, the mass ratio of V2O5 to Ag2O is 1:7.12.

[0009] The present invention also provides a method for preparing the above-mentioned composite thin-film cathode material for all-solid-state thin-film batteries, comprising the following steps:

[0010] 1) Clean and dry the substrate, then set aside.

[0011] 2) The substrate material obtained in step 1) is mounted on a magnetron sputtering substrate stage. Under an argon-oxygen mixed atmosphere, Ag metal target and V2O5 ceramic target are co-sputtered and deposited onto the substrate surface to obtain a composite thin film cathode material. In the composite thin film, the mass ratio of V2O5 to Ag2O is 1:(5.37-9.56).

[0012] Furthermore, in step 1), the substrate is any one of silicon wafer, glass, polyimide film, stainless steel, and nickel foil.

[0013] Furthermore, in step 2), the magnetron co-sputtering process conditions are: a vacuum level below 3 × 10⁻⁶. -4 Pa, sputtering pressure is 0.5 Pa;

[0014] In the argon-oxygen mixed atmosphere, the volumetric flow rate of argon and oxygen is (8-12):1.

[0015] Furthermore, the sputtering power of Ag2O is 5-10W, and the sputtering power of V2O5 is 60-100W (depending on the sputtering rate of different magnetron coating equipment and different target materials).

[0016] Furthermore, in the composite film, the mass ratio of V2O5 to Ag2O is 1:7.12.

[0017] The present invention also provides an application of the above-mentioned composite thin film cathode material in the fabrication of all-solid-state thin film batteries.

[0018] The present invention also provides an all-solid-state thin-film battery, wherein the positive electrode is made of the above-mentioned composite thin-film positive electrode material, the negative electrode is made of lithium metal as the negative electrode material, and LiPON is used as the solid electrolyte, and the positive electrode, solid electrolyte and negative electrode are assembled into a full battery.

[0019] Principle of this invention:

[0020] In the composite thin-film cathode material (Ag2O / V2O5 composite thin-film structure) of the present invention, Ag2O is uniformly dispersed in the form of crystalline particles in an amorphous V2O5 matrix. The mass ratio of Ag2O / V2O5 is (5.37-9.56):1. This composite thin-film cathode utilizes the nano-confinement effect of V2O5 to effectively suppress the agglomeration and structural degradation of Ag2O particles, thereby significantly improving the structural stability and cycle stability of the cathode material.

[0021] This invention controls the magnetron sputtering process conditions to adjust the sputtering rates of the Ag metal target and the V2O5 ceramic target, achieving an Ag2O / V2O5 mass ratio of (5.37-9.56):1. This appropriate Ag2O / V2O5 ratio ensures that V2O5 in the composite film effectively inhibits the aggregation of Ag2O particles, thereby improving the structural stability and cycle stability of the material.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention effectively suppresses the agglomeration and structural deterioration of Ag2O particles through the nano-confinement effect of amorphous V2O5, significantly improving the cycle life of pure Ag2O materials and realizing their transformation from primary battery cathode materials to recyclable secondary cathode materials.

[0024] 2. The composite thin-film cathode material of the present invention has high capacity and high energy density, and does not require annealing treatment. It is compatible with a variety of microelectronic integration processes and is suitable for the fabrication needs of micro energy storage devices.

[0025] 3. The preparation method of the present invention can achieve the compactness and flatness of the film at the nanoscale, with high repeatability and high yield, laying a solid foundation for large-scale application and market promotion.

[0026] In summary, this invention utilizes amorphous V₂O₅ to modify Ag₂O to prepare a high-capacity, anneal-free composite thin-film cathode. This composite thin-film cathode is deposited on various substrates via magnetron co-sputtering, resulting in a dense and uniform film. This invention requires no annealing treatment and is compatible with various thermistor materials and devices. Attached Figure Description

[0027] Figure 1Photograph of the composite thin-film cathode material AVO-5W-nickel prepared in Example 1, based on nickel foil;

[0028] Figure 2 SEM images of the surface and cross-section of the composite thin film cathode materials AVO-5W-nickel, AVO-4W-nickel and AVO-6W-nickel prepared in Examples 1-3, and the pure Ag2O thin film cathode materials pure Ag2O-nickel and pure V2O5 thin film cathode materials pure V2O5-nickel prepared in Comparative Examples 1 and 3.

[0029] (a) SEM images of the surface and cross-section of the composite thin-film cathode material AVO-4W-nickel;

[0030] (b) SEM images of the surface and cross-section of the composite thin-film cathode material AVO-5W-nickel;

[0031] (c) SEM images of the surface and cross-section of the composite thin-film cathode material AVO-6W-nickel;

[0032] (d) is a SEM image of the surface and cross-section of pure Ag2O-nickel thin film cathode material;

[0033] (e) is a SEM image of the surface and cross-section of pure V2O5-nickel thin film cathode material;

[0034] Figure 3 XRD patterns of composite thin film cathode materials AVO-5W-304, AVO-4W-304 and AVO-6W-304, as well as pure Ag2O thin film cathode material pure Ag2O-304 and pure V2O5 thin film cathode material pure V2O5-304.

[0035] (a) XRD patterns of composite thin film cathode materials AVO-5W-304, AVO-4W-304 and AVO-6W-304.

[0036] (b) is the XRD pattern of the pure Ag2O thin film of pure Ag2O-304, a pure Ag2O thin film cathode material.

[0037] (c) is the XRD pattern of pure V2O5 thin film of pure V2O5-304, a pure V2O5 thin film cathode material.

[0038] Figure 4 Comparison of cycling performance tests at low current for half-cells (coin cells 1~3 and control cells 1~2) made with three composite thin-film cathode materials: AVO-5W-nickel, AVO-4W-nickel, and AVO-6W-nickel, as well as pureAg2O-nickel and pureV2O5-nickel.

[0039] Figure 5 Comparison of half-cell cycling performance under high current for three composite thin-film cathode materials: AVO-5W-nickel, AVO-4W-nickel, and AVO-6W-nickel, as well as pureAg2O-nickel and pureV2O5-nickel.

[0040] Figure 6 A solid-state thin-film battery made of AVO-5W-nickel composite thin-film cathode material is used in the detection of small sensor devices. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can understand it.

[0042] Example 1

[0043] A method for preparing AVO-5W-nickel composite thin-film cathode material for all-solid-state thin-film batteries includes the following steps:

[0044] 1) Clean and dry the nickel foil, and set aside for later use;

[0045] 2) A magnetron sputtering device and a vacuum thermal evaporation device were placed in a glove box (H2O≤0.01 ppm, O2≤0.01 ppm). The substrate material obtained in step 1) was then fixed onto the substrate of the magnetron sputtering device (Wuhan Pudi Vacuum Technology Co., Ltd., model: PD-400S). Both the Ag metal target and the V2O5 ceramic target were fixed, with a target-substrate distance of 7 cm from the substrate. The substrate was rotated at 10 rpm, and 50.0 sccm Ar and 5.0 sccm O2 were introduced through a volumetric flow controller. The temperature was 25 ℃, and the vacuum degree was less than 3×10⁻⁶. -4 Under the conditions of sputtering pressure of 0.5 Pa, V2O5 ceramic target power fixed at 60 W, and Ag metal target power set at 5 W, a composite film was formed by co-sputtering deposition on the substrate surface to obtain the composite film cathode material AVO-5W-nickel, wherein the thickness of the composite film is 570 nm, and the mass ratio of V2O5 to Ag2O is 1:7.12.

[0046] like Figure 1 As shown: In the composite thin film cathode material AVO-5W-nickel, the composite thin film on the nickel foil surface is gray-black and the film layer is dense, which lays the foundation for its good electrochemical performance.

[0047] Example 2

[0048] The method for preparing the composite thin-film cathode material AVO-4W-nickel in this embodiment is basically the same as that in Example 1, except that:

[0049] A composite thin film was formed by co-sputtering deposition on the substrate surface under an Ag metal target power of 4W, resulting in a composite thin film cathode material AVO-4W-nickel. The thickness of the composite thin film was 460 nm, and the mass ratio of V2O5 to Ag2O was 1:5.37.

[0050] Example 3

[0051] The method for preparing the composite thin-film cathode material AVO-6W-nickel in this embodiment is basically the same as that in Example 1, except that:

[0052] A composite thin film was formed by co-sputtering deposition on the substrate surface under an Ag metal target power of 6 W, resulting in a composite thin film cathode material AVO-6W-nickel. The thickness of the composite thin film was 710 nm, and the mass ratio of V2O5 to Ag2O was 1:9.56.

[0053] Examples 4-6

[0054] The methods used to prepare the three composite thin-film cathode materials AVO-5W-304, AVO-4W-304, and AVO-6W-304 in Examples 4-6 are basically the same as those used in Examples 1, 2, and 3, with the following differences:

[0055] The substrates for the three composite thin-film cathode materials, AVO-5W-304, AVO-4W-304, and AVO-6W-304, are all made of 304 stainless steel.

[0056] Example 7

[0057] The method for preparing the composite thin-film cathode material AVO-5W-glass in Example 7 is basically the same as that in Example 1, except that:

[0058] The substrate for the composite thin-film cathode material AVO-5W-glass is a glass sheet.

[0059] Comparative Example 1

[0060] The preparation method of pure Ag2O-nickel as the positive electrode material of pure Ag2O thin film includes the following steps:

[0061] 1) Clean and dry the nickel foil, and set aside for later use;

[0062] 2) A magnetron sputtering device and a vacuum thermal evaporation device were placed in a glove box (H2O≤0.01 ppm, O2≤0.01 ppm). The substrate material obtained in step 1) was then fixed onto the substrate of the magnetron sputtering device (Wuhan Pudi Vacuum Technology Co., Ltd., model: PD-400S). An Ag metal target was fixed at a target-substrate distance of 7 cm from the substrate. The substrate was rotated at 10 rpm. 50.0 sccm Ar and 5.0 sccm O2 were introduced through a volumetric flow controller. The temperature was 25 ℃ and the vacuum degree was less than 3×10⁻⁶. -4 Under the conditions of sputtering pressure of 0.5 Pa and Ag metal target power of 5 W, a pure Ag2O thin film (i.e., pure Ag2O) was formed on the substrate surface by sputtering deposition, resulting in a pure Ag2O-nickel cathode material with a thickness of 513 nm.

[0063] Comparative Example 2

[0064] The method for preparing the positive electrode material pure Ag2O-304 in this comparative example is basically the same as that in Comparative Example 1, except that:

[0065] The substrate for the positive electrode material of pure Ag2O thin film, pure Ag2O-304, is selected using 304 stainless steel.

[0066] Comparative Example 3

[0067] The preparation method of pure V2O5-nickel as the positive electrode material of pure V2O5 thin film includes the following steps:

[0068] 1) Clean and dry the nickel foil, and set aside for later use;

[0069] 2) A magnetron sputtering device and a vacuum thermal evaporation device were placed in a glove box (H2O≤0.01 ppm, O2≤0.01 ppm). The substrate material obtained in step 1) was then fixed onto the substrate of the magnetron sputtering device (Wuhan Pudi Vacuum Technology Co., Ltd., model: PD-400S). An Ag metal target was fixed at a target-substrate distance of 7 cm from the substrate. The substrate was rotated at 10 rpm. 50.0 sccm Ar and 5.0 sccm O2 were introduced through a volumetric flow controller. The temperature was 25 ℃ and the vacuum degree was less than 3×10⁻⁶. -4 Under the conditions of sputtering pressure of 0.5 Pa and V2O5 ceramic target power of 60 W, a pure V2O5 thin film (i.e., pure V2O5) was formed on the substrate surface by sputtering deposition, resulting in a pure V2O5-nickel cathode material with a thickness of 81 nm.

[0070] Comparative Example 4

[0071] The method for preparing the pure V2O5 thin film cathode material pure V2O5-304 in this comparative example is basically the same as the method in comparative example 3, except that:

[0072] The substrate for the pure V2O5 thin film cathode material, pure V2O5-304, is made of 304 stainless steel.

[0073] 1. Observation of the thin film morphology of composite thin film cathode materials

[0074] 1.1 Method

[0075] The surface and cross-section of the composite thin film cathode material AVO-5W-nickel prepared in Example 1 and the pure Ag2O-nickel foil prepared in Comparative Example 1 were scanned using a scanning electron microscope (SEM).

[0076] 1.2 Conclusion

[0077] like Figure 2 As shown: The surface of the composite thin film cathode material AVO-5W-nickel is very dense and flat. In the composite film, Ag2O particles are uniformly dispersed without obvious agglomeration. In contrast, many obvious large Ag2O particles with a particle size of 200-500 nm are seen in pure Ag2O-nickel.

[0078] Therefore, it can be concluded that in AVO-5W-nickel, amorphous V2O5 effectively inhibits the agglomeration of Ag2O crystal particles.

[0079] 2. Crystal structure characterization of thin films in cathode materials

[0080] 2.1 Methods

[0081] The thin film crystal structures of three composite thin film cathode materials, AVO-5W-304, AVO-4W-304, AVO-6W-304, pure Ag2O-304, and pure V2O5-304, were characterized by X-ray diffraction (XRD).

[0082] 2.2 Conclusion

[0083] like Figure 3 As shown: In the composite films of the three composite thin-film cathode materials AVO-5W-304, AVO-4W-304, and AVO-6W-304, Ag2O is crystalline, while V2O5 is amorphous; crystalline Ag2O is also observed in the film of pure Ag2O-304; and crystalline V2O5 is also observed in the film of pureV2O5-304. This indicates that we have successfully constructed a composite film in which crystalline Ag2O is embedded in amorphous V2O5, thereby utilizing the stability of amorphous V2O5 to improve the stability of Ag2O crystals.

[0084] Examples 8-10

[0085] Three composite thin-film cathode materials, AVO-5W-nickel, AVO-4W-nickel, and AVO-6W-nickel, prepared in Examples 1, 2, and 3, were used to make cathodes and lithium metal to make anodes. PP2500 separators (purchased from Duoduo Chemical Reagent Network) and lithium-sulfur electrolyte LS-002 were used to assemble coin cells 1 to 3.

[0086] Comparative Examples 5-6

[0087] Meanwhile, positive electrodes were prepared using pure Ag2O-nickel prepared in Comparative Example 1 and pure V2O5-nickel prepared in Comparative Example 3, respectively, and control cells 1-2 were prepared under the same process.

[0088] 3. Using the Xinwei battery tester, the test was conducted at 12.7 μA·cm. -2 and 51.0 μA·cm -2 Constant current tests were performed on all batteries at a current density of [value missing].

[0089] like Figure 4 The results showed that the specific capacity of the three coin cells 1-3 was significantly higher than that of the two control cells 1-2. Among them, coin cell 1 exhibited the best cycle performance and the highest capacity. The initial discharge capacity of coin cell 1 reached 171.0 μA·cm⁻¹. -2 μm -1 After 100 cycles, the capacity retention rate of the coin cell was 82%, with an average coulombic efficiency approaching 100%; while the control cell 1 only retained 11% of its capacity after 100 cycles. In long-cycle tests at higher current densities, the coin cell 1 still retained 73% of its capacity after 1000 cycles, demonstrating significantly better cycle stability than the control cell 1. Figure 5 ).

[0090] The above results indicate that the composite film cathode materials AVO-5W-nickel, AVO-4W-nickel, and AVO-6W-nickel effectively improve the electrochemical cycling performance of Ag2O materials. Among them, the composite film cathode material AVO-5W-nickel shows the best improvement in electrochemical cycling performance of Ag2O materials.

[0091] Example 11

[0092] Using a glass sheet as a substrate, the composite thin-film positive electrode material AVO-5W-glass prepared in Example 7 was used as the positive electrode, LiPON was used as the solid electrolyte, lithium metal was used as the negative electrode material, and platinum (Pt) was used as the positive electrode current collector and copper (Cu) was used as the negative electrode current collector to assemble an all-solid-state thin-film battery.

[0093] An all-solid-state thin-film battery assembled based on the composite thin-film cathode material AVO-5W-glass has practical power supply capability and successfully lit a green LED light. Figure 6 This further validates its applicability as a micro power source.

[0094] All other parts not described in detail are existing technologies. Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A composite thin-film cathode material for all-solid-state thin-film batteries, characterized in that: The composite thin film cathode material includes a substrate and a composite thin film covering the surface of the substrate. The composite thin film is composed of V2O5 and Ag2O, and the mass ratio of V2O5 to Ag2O in the composite thin film is 1:(5.37-9.56).

2. The composite thin-film cathode material according to claim 1, characterized in that: The thickness of the composite film is 300-2000 nm.

3. The composite thin-film cathode material according to claim 1 or 2, characterized in that: In the composite film, the mass ratio of V2O5 to Ag2O is 1:7.

12.

4. A method for preparing the composite thin-film cathode material for an all-solid-state thin-film battery as described in claim 1, characterized in that: Includes the following steps: 1) Clean and dry the substrate, then set aside. 2) The substrate material obtained in step 1) is mounted on a magnetron sputtering substrate stage. Under an argon-oxygen mixed atmosphere, Ag metal target and V2O5 ceramic target are co-sputtered and deposited onto the substrate surface to obtain a composite thin film cathode material. In the composite thin film, the mass ratio of V2O5 to Ag2O is 1:(5.37-9.56).

5. The preparation method according to claim 4, characterized in that, In step 1), the substrate is any one of silicon wafer, glass, polyimide film, stainless steel and nickel foil.

6. The preparation method according to claim 4, characterized in that, In step 2), the magnetron co-sputtering process conditions are: vacuum level below 3 × 10⁻⁶. -4 Pa, sputtering pressure is 0.5 Pa; In the argon-oxygen mixed atmosphere, the volumetric flow rate of argon and oxygen is (8-12):

1.

7. The preparation method according to any one of claims 4 to 6, characterized in that, In step 2), the sputtering power of the Ag metal target is 5-10W, and the sputtering power of the V2O5 ceramic target is 60-100W.

8. The preparation method according to claim 7, characterized in that, In the composite film, the mass ratio of V2O5 to Ag2O is 1:7.

12.

9. The application of the composite thin-film cathode material according to any one of claims 1 to 3 in the fabrication of an all-solid-state thin-film battery.

10. A fully solid-state thin-film battery, characterized in that: In the all-solid-state thin-film battery, the positive electrode is made of the composite thin-film positive electrode material as described in any one of claims 1 to 3, the negative electrode is made of lithium metal as the negative electrode material, and LiPON is used as the solid electrolyte. The positive electrode, solid electrolyte and negative electrode are assembled into a full battery.

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