Light-assisted all-solid-state thin-film lithium battery with light-trapping structure on incident light side and preparation method thereof

Abstract

This invention belongs to the field of electrochemical energy storage devices and discloses a light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side and its fabrication method. The light-assisted all-solid-state thin-film lithium battery consists of a transparent substrate, a micro / nano light-trapping structure, a transparent current collector layer, a first electrode active layer, a solid electrolyte layer, a second electrode active layer, and a second current collector layer. This invention achieves anti-reflection and anti-reflection functions, extends the optical path, or enhances the near-field by constructing a light-trapping structure on the incident light side of the electrode, including subwavelength graded refractive index structures, diffraction or scattering structures, photonic crystal structures, microlens array structures, and metal surface plasmon structures. This improves the coupling and absorption efficiency of the electrode thin film for incident light, enhances charge transport and ion migration dynamics, and thus improves the electrochemical performance of the light-assisted solid-state thin-film battery.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage devices, and particularly relates to a light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side and its preparation method. Background Technology

[0002] The ever-increasing energy demand is driving the large-scale application of renewable energy, while the efficiency and economic feasibility of energy applications require the development of more efficient energy storage technologies. As a strong competitor to traditional batteries, all-solid-state thin-film batteries offer advantages such as high safety, miniaturization, and integrability, and are commonly used in on-chip power supplies, micro-devices, and power supply for special environments. To overcome the limitations of traditional electrochemical processes in mass transfer and charge transfer kinetics, introducing light-assisted strategies to participate in / regulate interfacial charge transfer and reaction kinetics through photogenerated carriers is a promising development direction.

[0003] However, the electrode active layer of thin-film batteries is usually a nanometer to micrometer-scale thin film. The limited thickness causes problems such as insufficient effective optical path, large interface reflection loss, and sensitivity to incident angle in the light-participating or photoelectrochemical coupling modes. This limits the absorption efficiency of the positive electrode to incident light, and consequently affects the promoting effect of photoinduced charge carriers and photothermal effects on the electrochemical process.

[0004] In existing technologies, various light-trapping and anti-reflection structures for thin-film devices have been proposed in the field of optics. However, there is still room for improvement in integrating these structures into the electrode side to adapt to all-solid-state thin-film battery stacking systems and form a universal solution that can cover multiple materials and processes. Regarding the existing published patent CN112310468A (Photo-assisted Enhanced Secondary Battery and its Fabrication Method), its incident light path relies solely on the transmittance of the transparent substrate and current collector, without setting any light-trapping structure on the light incident side. This results in strong reflection loss of the incident light, low light energy coupling efficiency, and difficulty in achieving broad-spectrum, wide-angle light absorption. This limits the extent to which the photo-assisted effect can improve battery performance.

[0005] Therefore, developing a light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side, and further improving the battery's capacity, cycle stability, and energy efficiency under illumination conditions by optimizing the light coupling and absorption path, has significant research value and application prospects. Summary of the Invention

[0006] To overcome the various limitations of the aforementioned light-assisted all-solid-state thin-film lithium batteries, this invention aims to provide a light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side. The light-trapping structure is used to achieve anti-reflection and anti-reflection functions, extend the optical path, or enhance the near-field function, thereby improving the coupling and absorption efficiency of the electrode film to the incident light, further improving charge transport and ion migration dynamics, and achieving broad coverage in terms of structure type, material system, and process route, enhancing the versatility and anti-circumvention properties of the solution.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: On one hand, the present invention provides a light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side, comprising a transparent substrate, and a transparent current collector layer, a first electrode active layer, a solid electrolyte layer, a second electrode active layer, and a second current collector layer sequentially disposed on the transparent substrate along the incident light direction; wherein, the transparent current collector layer and the first electrode active layer constitute a first electrode, the second electrode active layer and the second current collector layer constitute a second electrode, the incident light side is the first electrode side, and at least one of the surfaces of the transparent substrate, the transparent current collector layer and the first electrode active layer facing the incident light is provided with a micro-nano light-trapping structure, the micro-nano light-trapping structure being used to improve the coupling and absorption of incident light by the first electrode active layer; the first electrode is a positive electrode or a negative electrode; the second electrode is a negative electrode or a positive electrode opposite to the first electrode.

[0008] Further, the transparent substrate is one or more of quartz, glass, sapphire, transparent ceramic, and transparent polymer; the transparent current collector layer is ITO or FTO; the first electrode active layer and the second electrode active layer are positive electrode active materials and negative electrode active materials, respectively, wherein the positive electrode active material is lithium cobalt oxide or titanium dioxide, and the negative electrode active material is metallic lithium or titanium dioxide; the solid electrolyte layer is amorphous lithium phosphorus oxynitride nitrogen (LiPON), i.e., nitrogen-doped lithium phosphate; the material of the micro / nano light-trapping structure is one or more of inorganic dielectric materials, transparent conductive materials, metallic materials, and polymer materials.

[0009] Furthermore, the micro / nano light-trapping structure type is one or more of the following: subwavelength graded refractive index structure, diffraction or scattering structure, photonic crystal structure, microlens array structure, and metal surface plasmon structure.

[0010] The subwavelength graded refractive index structure is composed of multiple subwavelength-sized protrusions or depressions, forming an equivalent refractive index graded layer at the interface between the external medium and the electrode side to reduce reflection loss. The subwavelength graded refractive index structure can be one or more of nanocone arrays, nanopillar arrays, nanohemispherical arrays, and nanopore arrays. The characteristic size of the protrusions or depressions is 10 nm to 2000 nm, the structure height is 10 nm to 5000 nm, and the structure period or average spacing is 50 nm to 3000 nm. By forming an equivalent refractive index continuous transition layer between air and the device surface, the subwavelength graded refractive index structure reduces Fresnel reflection caused by abrupt changes in refractive index and improves incident light coupling efficiency under broad spectrum and wide incident angle conditions, thereby achieving light trapping and anti-reflection and increasing the incident light flux of subsequent absorption layers.

[0011] The diffraction or scattering structure is used to diffract or scatter incident light and couple it into an oblique incidence propagation path or a quasi-guided mode propagation path, thereby extending the effective optical path within the electrode film. The diffraction or scattering structure is one or more of a one-dimensional grating, a two-dimensional grating, a subwavelength grating, a chirped grating, a sawtooth grating, a trapezoidal grating, and a quasi-random texture structure. The grating period is 100 nm to 5000 nm, and the grating height is 20 nm to 2000 nm. By providing lateral momentum, the diffraction or scattering structure causes incident light to diffract or scatter, coupling the light into an oblique incidence propagation path and / or a confined mode propagation path, extending the effective optical path within the absorption layer and increasing the probability of multiple traversals, thereby achieving light trapping and enhanced absorption.

[0012] The photonic crystal structure is one or more of a one-dimensional multilayer periodic structure, a two-dimensional aperture array structure, a two-dimensional pillar array structure, and a three-dimensional periodic structure, used to form a bandgap effect or resonant mode to enhance electrode absorption. The period of the photonic crystal structure is 100 nm to 5000 nm, the aperture or pillar diameter is 50 nm to 3000 nm, and the structural depth is 50 nm to 5000 nm. The photonic crystal structure generates a bandgap effect and / or resonant confined modes through periodic modulation of the dielectric constant or refractive index, causing the incident light to form a local field enhancement or strong coupling with the confined mode near the structure. By mode reuse and energy retention, the light energy density near the absorption layer is increased, thereby achieving light trapping and absorption enhancement.

[0013] The microlens array structure is one or more of a microlens array, a microdot array, and a microprism array, used to change the incident angle distribution or locally converge incident light to improve electrode coupling and absorption. The lens diameter or array pitch of the microlens array structure is 1 micrometer to 2000 micrometers, and the lens height is 0.2 micrometers to 500 micrometers. By changing the angular distribution and spatial energy distribution of the incident light, the microlens array structure enables the light to form a larger incident angle cone and / or locally converged beam inside the device, reducing direct reflection and increasing the light reflection and path length in the thin film stack, thereby achieving light trapping and path extension and enhanced absorption over a wide incident angle range.

[0014] The metal surface plasmon structure is used to excite surface plasmon polaritons and / or localized surface plasmons under incident light to enhance the light field intensity or scattering coupling on the electrode side, thereby improving the coupling and absorption of incident light by the electrode layer. The metal surface plasmon structure is one or more of the following: metal thin film, metal nanoparticles, metal nanoarray, metal nanopore array, and metal nanoantenna, wherein the metal is one or more of silver, gold, aluminum, and copper. The metal surface plasmon structure concentrates the incident light energy in the vicinity of the electrode side and improves the coupling efficiency with the absorption layer or confined modes by generating near-field enhancement and strong scattering effects at the metal interface, thereby achieving localized light trapping and enhanced absorption.

[0015] On the other hand, the present invention provides a method for preparing a light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side, comprising the following steps: S1. Prepare a transparent substrate and perform surface treatment to obtain a clean transparent substrate; S2. A transparent current collector layer on the incident light side is formed on a transparent substrate; S3. Forming micro-nano light-trapping structures on a transparent current collector layer; S4. A first electrode active layer is formed on the transparent current collector layer after the formation of the micro-nano light trapping structure, wherein the first electrode is a positive electrode or a negative electrode. S5. A solid electrolyte layer is formed on the first electrode active layer; S6. A second electrode active layer is formed on the solid electrolyte layer, wherein the second electrode is a negative electrode or a positive electrode opposite to the first electrode; S7. A second current collector layer is formed on the active layer of the second electrode to achieve external electrical connection.

[0016] Furthermore, the transparent current collector layer, the first electrode active layer, the second electrode active layer, the solid electrolyte layer, and the second current collector layer are all formed by thin film deposition processes, wherein the thin film deposition processes are one or more of physical vapor deposition, chemical vapor deposition, atomic layer deposition, sol-gel film formation, coating film formation, and electrochemical deposition; the light-trapping structure is formed by patterning processes, wherein the patterning processes are one or more of nanoimprinting, photolithography combined with etching, interference lithography, template replication, colloidal lithography or self-assembly, and laser processing.

[0017] Furthermore, the detailed steps of the preparation method are as follows: S1. Perform ultrasonic cleaning on the purchased FTO etched glass substrate to remove surface impurities, obtain a clean and transparent substrate, and store it in ethanol for later use.

[0018] S2. After removing the glass substrate and drying it, gold nanoparticles are deposited on the FTO etched surface using a gold sputtering machine to form a plasmonic light-trapping structure.

[0019] S3. Cover the gold-plated glass substrate with an electrode mold and fix it to the substrate tray. Place it in the sputtering position of the magnetron sputtering instrument and fix it. Place the titanium target in the target fixing position. Set the atmosphere to an argon-oxygen environment and perform magnetron sputtering to obtain a titanium dioxide thin film, which serves as the first electrode, i.e., the positive electrode.

[0020] S4. After the positive electrode deposition is completed, cover the tab area of ​​the positive electrode with a mold, then fix the substrate on the tray and place it in the sputtering position of the magnetron sputtering instrument. Use a lithium phosphate target to perform magnetron sputtering deposition of solid electrolyte LiPON in a nitrogen atmosphere at room temperature.

[0021] S5. Remove the substrate with the electrolyte deposited, replace the mold with the negative electrode cover mold and fix it on the substrate tray, place it in the substrate stage position in the evaporation device, and use thermal evaporation to deposit lithium as the second electrode, i.e., the negative electrode, in a vacuum environment. The battery after the coating is removed is a light-assisted all-solid-state thin-film lithium battery with a plasmonic light-trapping structure added to the electrode side.

[0022] The beneficial effects of this invention are as follows: (1) Improve the incident coupling and effective optical path on the electrode side, and significantly enhance the absorption efficiency. By introducing a light trapping structure on the incident light side of the electrode, the interface reflection loss is reduced and the light energy is more effectively confined to the vicinity of the electrode, so that the thin film electrode can still obtain higher light absorption and stronger light field residence even with a thinner thickness.

[0023] (2) Enhance the photo-assisted effect and improve electrochemical kinetics, thereby improving charge-discharge performance and stability. The light-trapping structure increases the light energy density and local interaction intensity on the electrode side, which is conducive to triggering or enhancing the photogenerated carriers and photothermal coupling process, reducing the polarization and charge transfer impedance at the electrode-solid electrolyte interface, promoting ion migration and charge transport, and thus achieving faster response, higher rate performance and better cycle stability under the same voltage window. Attached Figure Description

[0024] Figure 1 A simplified diagram of the overall structure of a light-assisted solid-state thin-film lithium-ion battery with a light-trapping structure added to the light-incident side.

[0025] Figure 2 This is a schematic diagram of a subwavelength graded refractive index structure; the top image is a planar top view, and the bottom image is a cross-sectional view (Note: the dashed lines in the planar top view represent the cross-section of the cross-section).

[0026] Figure 3 This is a schematic diagram of the diffraction and scattering structure; the top image is a planar top view, and the bottom image is a cross-sectional view (Note: the dashed lines in the planar top view represent the cross-section of the cross-section).

[0027] Figure 4 This is a schematic diagram of a photonic crystal structure; the top image is a planar top view, and the bottom image is a cross-sectional view (Note: the dashed lines in the planar top view represent the cross-section of the cross-section).

[0028] Figure 5 This is a schematic diagram of a microlens array structure; the top image is a planar top view, and the bottom image is a cross-sectional view (Note: the dashed lines in the planar top view represent the cross-section of the cross-section).

[0029] Figure 6 This is a schematic diagram of the plasmonic structure on a metal surface; the top image is a planar top view, and the bottom image is a cross-sectional view. (Note: The dashed lines in the planar top view represent the cross-section of the cross-section).

[0030] Figure 7 This is a complete sample image of the light-assisted all-solid-state thin-film lithium battery with a metal surface plasmon light-trapping structure on the incident light side in Example 5.

[0031] Figure 8 The image shows a cross-sectional view of a light-assisted all-solid-state thin-film lithium battery with a metal surface plasmon light-trapping structure on the incident light side, obtained by focused ion beam cutting (FIB) in Example 5.

[0032] Figure 9This is a comparison of the charge-discharge curves of the light-assisted all-solid-state thin-film lithium battery with a metal surface plasmon light-trapping structure on the incident light side and the corresponding battery without the light-trapping structure in Example 5, under illumination and dark conditions. Au@TiO2-L / TiO2-L represent the charge-discharge curves of the light-assisted all-solid-state thin-film lithium battery with the metal surface plasmon light-trapping structure on the incident light side and the corresponding battery without the light-trapping structure, respectively, under illumination. Au@TiO2-D / TiO2-D represent the charge-discharge curves of the light-assisted all-solid-state thin-film lithium battery with the metal surface plasmon light-trapping structure on the incident light side and the corresponding battery without the light-trapping structure, respectively, under dark conditions.

[0033] Explanation of reference numerals in the attached figures: 1-Transparent substrate, 2-Transparent current collector layer, 3-Micro-nano light trapping structure (taking moth-eye subwavelength graded refractive index light trapping structure as an example), 4-First electrode active layer, 5-Solid electrolyte layer, 6-Second electrode active layer, 7-Second current collector layer. Detailed Implementation

[0034] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0035] like Figure 1 As shown, the present invention provides a light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side, including a transparent substrate 1, and a transparent current collector layer 2, a first electrode active layer 4, a solid electrolyte layer 5, a second electrode active layer 6, and a second current collector layer 7 sequentially disposed on the transparent substrate along the incident light direction; wherein, the transparent current collector layer and the first electrode active layer constitute the first electrode, the second electrode active layer and the second current collector layer constitute the second electrode, the incident light side is the first electrode side, and at least one of the surfaces of the transparent substrate, the transparent current collector layer and the first electrode active layer facing the incident light is provided with a micro-nano light-trapping structure 3, the micro-nano light-trapping structure being used to improve the coupling and absorption of incident light by the first electrode active layer; the first electrode is a positive electrode or a negative electrode; the second electrode is a negative electrode or a positive electrode opposite to the first electrode. Example 1

[0036] Design of a light-assisted all-solid-state thin-film lithium battery with a subwavelength graded refractive index light-trapping structure on the incident light side A transparent substrate is provided, a transparent current collector layer is formed on the transparent substrate, and then a subwavelength graded refractive index structure is formed on the transparent current collector layer. For example... Figure 2The subwavelength graded refractive index structure is a hexagonal close-packed nanocone array. The nanocones are periodically arranged along the plane to form hexagonal close-packed units with an array period of 100 nanometers to 800 nanometers, a base feature size of 50 nanometers to 600 nanometers, and a height of 200 nanometers to 1500 nanometers.

[0037] After forming the hexagonal close-packed nanocone array, an incident light side first electrode active layer, a solid electrolyte layer, a second electrode active layer, and a second current collector layer or electrical connection structure are formed on it to obtain a light-assisted all-solid-state thin-film lithium battery, wherein the first electrode is a positive electrode or a negative electrode, and the second electrode is a negative electrode or a positive electrode opposite to the first electrode.

[0038] The hexagonal close-packed nanocone array forms an equivalent refractive index continuous transition layer between air and the device surface, reducing incident interface reflection and improving incident light coupling efficiency, thereby enhancing electrode-side light absorption. Example 2

[0039] Design of light-assisted all-solid-state thin-film lithium batteries with diffraction or scattering trapping structures on the incident light side A transparent substrate is provided, a transparent current collector layer is formed on the transparent substrate, and then a diffraction or scattering structure is formed on the transparent current collector layer. For example... Figure 3 The diffraction or scattering structure is a one-dimensional striped grating structure, with grating stripes extending parallel in the same direction and repeating periodically. The grating period is 300 nanometers to 1500 nanometers, and the grating height is 50 nanometers to 800 nanometers.

[0040] After forming the one-dimensional striped grating, an incident light side first electrode active layer, a solid electrolyte layer, a second electrode active layer, and a second current collector layer or electrical connection structure are sequentially formed on the substrate to obtain a light-assisted all-solid-state thin-film lithium battery, wherein the first electrode is a positive electrode or a negative electrode, and the second electrode is a negative electrode or a positive electrode opposite to the first electrode.

[0041] The one-dimensional striped grating provides lateral momentum to the incident light, causing it to diffract and couple into an oblique propagation path, thereby extending the effective optical path within the electrode film and enhancing absorption. Example 3

[0042] Design of light-assisted all-solid-state thin-film lithium batteries with photonic crystal light-trapping structure on the incident light side A transparent substrate is provided, a transparent current collector layer is formed on the transparent substrate, and then a photonic crystal structure is formed on the transparent current collector layer. For example... Figure 4 The photonic crystal structure is a two-dimensional periodic aperture array structure. The aperture array is periodically distributed in a plane, with a period of 300 nanometers to 3000 nanometers, an aperture of 150 nanometers to 1500 nanometers, and a structural depth of 100 nanometers to 3000 nanometers.

[0043] After forming the two-dimensional periodic hole array, an incident light side first electrode active layer, a solid electrolyte layer, a second electrode active layer, and a second current collector layer or electrical connection structure are sequentially formed on the substrate to obtain a light-assisted all-solid-state thin-film lithium battery, wherein the first electrode is a positive electrode or a negative electrode, and the second electrode is a negative electrode or a positive electrode opposite to the first electrode.

[0044] The two-dimensional periodic aperture array forms a resonant confined mode through periodic refractive index modulation, which causes energy retention and local field enhancement of incident light on the electrode side, thereby improving light absorption on the electrode side. Example 4

[0045] Design of a light-assisted all-solid-state thin-film lithium battery with a microlens array light-trapping structure on the incident light side A transparent substrate is provided, a transparent current collector layer is formed on the transparent substrate, and then a first electrode active layer, a solid electrolyte layer, a second electrode active layer, and a second current collector layer or an electrical connection structure are sequentially formed on the transparent current collector layer to obtain a light-assisted all-solid-state thin-film lithium battery, wherein the first electrode is a positive electrode or a negative electrode, and the second electrode is a negative electrode or a positive electrode opposite to the first electrode.

[0046] Further, a microlens array light-trapping structure is formed on a transparent substrate. For example... Figure 5 The microlens array structure is a hexagonal close-packed microlens array, with each microlens having a dome-shaped structure. The microlenses are arranged in a hexagonal close-packed configuration in a plane, with a lens diameter or array pitch ranging from 10 micrometers to 300 micrometers and a lens height ranging from 1 micrometer to 80 micrometers.

[0047] The hexagonal close-packed microlens array alters the angular distribution of incident light and forms local convergence, making it easier for light to be reflected back in the thin film stack and increasing the path length, thereby enhancing light absorption on the electrode side. Example 5

[0048] Design and fabrication of light-assisted all-solid-state thin-film lithium batteries with plasmon light-trapping structures on the incident light side A transparent substrate is provided, a transparent current collector layer is formed on the transparent substrate, and then a metallic surface plasmon light trapping structure is formed on the transparent current collector layer. For example... Figure 6 The plasmon light trapping structure on the metal surface is a regular array of metal nanoparticles. The metal nanoparticles are periodically distributed in a lattice in the plane. The characteristic size of the nanoparticles is 10 nanometers to 200 nanometers, and the array period is 2 to 10 times the characteristic size.

[0049] After forming the plasmon light-trapping structure on the metal surface, a first electrode active layer, a solid electrolyte layer, a second electrode active layer, and a second current collector layer or electrical connection structure are sequentially formed on the substrate to obtain a light-assisted all-solid-state thin-film lithium battery, wherein the first electrode is a positive electrode or a negative electrode, and the second electrode is a negative electrode or a positive electrode opposite to the first electrode.

[0050] The gold nanoparticle array excites local surface plasmons under the action of incident light, generating near-field enhancement and scattering coupling, which increases the light field intensity on the electrode side and enhances coupling and absorption.

[0051] The specific preparation method is as follows: S1. The purchased FTO etched glass substrate was ultrasonically cleaned three times with anhydrous ethanol to remove surface impurities, resulting in a clean and transparent substrate, which was then stored in ethanol for later use.

[0052] S2. After removing the glass substrate and drying it, place it in the gold spraying machine, evacuate the chamber of the gold spraying machine to below 0.5Pa, set the duration to 10s, and the current to 10mA, and spray gold nanoparticles onto the FTO etched surface to form a plasmonic light trapping structure.

[0053] S3. Cover and fix the gold-plated glass substrate to the substrate tray using an electrode mold, place it in the sputtering position of the magnetron sputtering instrument cavity, and fix it in place. Place the titanium target in the target fixing position. Evacuate the sputtering chamber to 1.0 × 10⁻⁶. -5 Below Pa, the sputtering program is invoked to start sputtering. Gas is introduced and the gas flow rate is adjusted to 60 sccm (Ar:O2=50:10). The sputtering power is set to 80 W. After pre-sputtering for 1 minute, the target cover is removed, and the program is set to 28800 seconds for magnetron sputtering to obtain a titanium dioxide thin film, which serves as the first electrode, i.e., the positive electrode.

[0054] S4. After the positive electrode deposition is completed, cover the tab area of ​​the positive electrode with a mold, then fix the substrate on the tray and place it in the sputtering position of the magnetron sputtering instrument. Use lithium phosphate target, and evacuate the vacuum chamber to 1.0 × 10⁻⁶ at room temperature. -5 Below Pa, nitrogen gas was introduced, with the gas flow rate set to 90 sccm, the power set to 100 W, and the pre-sputtering time set to 1 min. The target cover was opened, and the sputtering deposition time was set to 36000 s. Solid electrolyte LiPON was deposited by magnetron sputtering.

[0055] S5. Remove the substrate with the deposited electrolyte, replace the mold with a negative electrode cover mold and fix it to the substrate tray, place it in the substrate stage position inside the evaporation apparatus, and add 12 lithium wafers to the crucible. Evacuate the chamber to 1.0 × 10⁻⁶. -5Below Pa, the program is set to heat the crucible and begin depositing metallic lithium as the second electrode, i.e., the negative electrode. The thickness of the deposited film is controlled to be around 2.5 µm. The battery after coating is then removed, which is a light-assisted all-solid-state thin-film lithium battery with a plasmonic light-trapping structure on the metal surface on the incident light side. The sample obtained after transparent glass encapsulation of the light-assisted all-solid-state thin-film lithium battery with a metal surface plasmon light-trapping structure on the incident light side, prepared in Example 5 of this invention, is shown below. Figure 7 As shown. Since the substrate where the first electrode is located is transparent glass, external light can pass through the substrate and irradiate the light-trapping structure and active electrode on the incident light side, thereby realizing the functions of battery light absorption and light-trapping structure enhancing light absorption.

[0056] The scanning electron microscope cross-sectional image of the light-assisted all-solid-state thin-film lithium battery with a metal surface plasmon light-trapping structure on the incident light side, prepared in Example 5 of this invention, after being cut by focused ion beam is shown below. Figure 8 As shown in the figure, the black particles marked by the red circle are gold nanoparticles formed after sputtering by the gold sputtering instrument. A plasmonic light-trapping structure with localized light trapping and enhanced absorption is formed on the surface. The upper part is the first electrode TiO2 with photoelectric effect, which is coupled with the light-trapping structure to form an active positive electrode with photoelectric conversion effect.

[0057] The light-assisted all-solid-state thin-film lithium battery with a plasmonic light-trapping structure on the incident light side obtained in Example 5 of this invention was subjected to constant current charge-discharge tests within a cutoff voltage range of 1.2V to 4.2V. The four sets of test results are as follows: Figure 9 As shown in the figure, the Au@TiO2 group represents the battery with a plasmon light-trapping structure on the incident light side, compared to the TiO2 group without the light-trapping structure. Under illumination (Au@TiO2-L / TiO2-L), it is evident that the battery with the added light-trapping structure exhibits a greater capacity increase compared to the battery under dark conditions (Au@TiO2-D / TiO2-D), and this increase remains stable. This demonstrates the enhancing effect of the light-trapping structure on the positive electrode light absorption of the battery through the plasmon effect.

[0058] It should be noted that the above embodiments are only used to illustrate the present invention. Those skilled in the art can make various improvements and substitutions to the structural form, material selection and process route without departing from the spirit of the present invention and the scope of protection of the claims. All such modifications and substitutions should fall within the protection scope of the present invention.

Claims

1. A light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side, characterized in that, The device includes a transparent substrate, and a transparent current collector layer, a first electrode active layer, a solid electrolyte layer, a second electrode active layer, and a second current collector layer sequentially disposed on the transparent substrate along the incident light direction. The transparent current collector layer and the first electrode active layer constitute a first electrode, and the second electrode active layer and the second current collector layer constitute a second electrode. The incident light side is the first electrode side, and at least one of the surfaces of the transparent substrate, the transparent current collector layer, and the first electrode active layer facing the incident light is provided with a micro / nano light-trapping structure. The micro / nano light-trapping structure is used to improve the coupling and absorption of incident light by the first electrode active layer. The first electrode is a positive or negative electrode; the second electrode is a negative or positive electrode opposite to the first electrode.

2. The light-assisted all-solid-state thin-film lithium battery according to claim 1, characterized in that, The micro / nano light-trapping structure type is one or more of the following: subwavelength graded refractive index structure, diffraction or scattering structure, photonic crystal structure, microlens array structure, and metal surface plasmon structure.

3. The light-assisted all-solid-state thin-film lithium battery according to claim 2, characterized in that, The micro / nano light-trapping structure is a subwavelength graded refractive index structure, which is composed of multiple subwavelength-sized protrusions or depressions, forming an equivalent refractive index graded layer at the interface between the external medium and the electrode side to reduce reflection loss. The subwavelength graded refractive index structure is one or more of nanocone arrays, nanopillar arrays, nanohemispherical arrays, and nanopore arrays. The characteristic size of the protrusions or depressions is 10 nanometers to 2000 nanometers, the structure height is 10 nanometers to 5000 nanometers, and the structure period or average spacing is 50 nanometers to 3000 nanometers.

4. The light-assisted all-solid-state thin-film lithium battery according to claim 2, characterized in that, The micro / nano light-trapping structure is a diffraction or scattering structure, which is used to diffract or scatter the incident light and couple it into an oblique incident propagation path or a quasi-guided mode propagation path, thereby extending the effective optical path within the electrode film; the diffraction or scattering structure is one or more of a one-dimensional grating, a two-dimensional grating, a subwavelength grating, a chirped grating, a sawtooth grating, a trapezoidal grating, and a quasi-random texture structure, with a grating period of 100 nanometers to 5000 nanometers and a grating height of 20 nanometers to 2000 nanometers.

5. The light-assisted all-solid-state thin-film battery according to claim 2, characterized in that, The micro / nano light-trapping structure is a photonic crystal structure, which is one or more of a one-dimensional multilayer periodic structure, a two-dimensional aperture array structure, a two-dimensional pillar array structure, and a three-dimensional periodic structure, used to form a bandgap effect or resonant mode to enhance electrode absorption; the period of the photonic crystal structure is 100 nanometers to 5000 nanometers, the aperture or pillar diameter is 50 nanometers to 3000 nanometers, and the structural depth is 50 nanometers to 5000 nanometers.

6. The light-assisted all-solid-state thin-film battery according to claim 2, characterized in that, The micro-nano light trapping structure is a microlens array structure, which is one or more of a microlens array, a microdome array, and a microprism array, used to change the incident angle distribution or locally converge the incident light to improve electrode coupling and absorption; the lens diameter or array pitch of the microlens array structure is 1 micrometer to 2000 micrometers, and the lens height is 0.2 micrometers to 500 micrometers.

7. The light-assisted all-solid-state thin-film battery according to claim 2, characterized in that, The micro / nano light-trapping structure is a metal surface plasmon structure. The metal surface plasmon structure is used to excite surface plasmon polaritons and / or local surface plasmons under the action of incident light to enhance the light field intensity or scattering coupling on the electrode side, thereby improving the coupling and absorption of incident light by the electrode layer. The metal surface plasmon structure is one or more of the following: metal thin film, metal nanoparticles, metal nanoarray, metal nanopore array, and metal nanoantenna, wherein the metal is one or more of silver, gold, aluminum, and copper.

8. A method for preparing a light-assisted all-solid-state thin-film lithium battery with a light-trapping structure on the incident light side, characterized in that, Includes the following steps: S1. Prepare a transparent substrate and perform surface treatment to obtain a clean transparent substrate; S2. A transparent current collector layer on the incident light side is formed on a transparent substrate; S3. Forming micro-nano light-trapping structures on a transparent current collector layer; S4. A first electrode active layer is formed on the transparent current collector layer after the formation of the micro-nano light trapping structure, wherein the first electrode is a positive electrode or a negative electrode. S5. A solid electrolyte layer is formed on the first electrode active layer; S6. A second electrode active layer is formed on the solid electrolyte layer, wherein the second electrode is a negative electrode or a positive electrode opposite to the first electrode; S7. A second current collector layer is formed on the active layer of the second electrode to achieve external electrical connection.

9. The preparation method according to claim 8, characterized in that, The transparent current collector layer, the first electrode active layer, the second electrode active layer, the solid electrolyte layer, and the second current collector layer are all formed by thin film deposition processes, which are one or more of physical vapor deposition, chemical vapor deposition, atomic layer deposition, sol-gel film formation, coating film formation, and electrochemical deposition. The light-trapping structure is formed by a patterning process, which is one or more of nanoimprinting, photolithography combined with etching, interference lithography, template replication, colloidal lithography or self-assembly, and laser processing.

10. The preparation method according to claim 8, characterized in that, The transparent substrate is one or more of quartz, glass, sapphire, transparent ceramic, and transparent polymer; the transparent current collector layer is ITO or FTO; the first electrode active layer and the second electrode active layer are positive electrode active materials and negative electrode active materials, respectively, wherein the positive electrode active material is lithium cobalt oxide or titanium dioxide, and the negative electrode active material is metallic lithium or titanium dioxide; the solid electrolyte layer is amorphous lithium phosphorus oxynitride nitrogen (LiPON), i.e., nitrogen-doped lithium phosphate; the material of the micro / nano light-trapping structure is one or more of inorganic dielectric materials, transparent conductive materials, metallic materials, and polymer materials.

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