A high-efficiency radiofluorescent isotope battery

Abstract

A high-efficiency radiofluorescent isotope solar cell includes a transparent encapsulated waveguide, a radioactive isotope source, a radiofluorescent crystal, a reflective layer, an anti-reflection layer, a photovoltaic unit, and an optical coupling layer. The top and bottom surfaces of the crystal are reflective layers, and the four sides are polished. The radioactive source and the crystal are alternately distributed, with the top and bottom layers being scintillation crystals. The transparent encapsulated waveguide is internally anti-reflective, and the radioactive source and the fluorescent layer are encapsulated to form a radiofluorescent module. The photovoltaic unit receives the fluorescence emitted from the side of the radiofluorescent module, and an optical coupling layer is loaded between them. By alternating the radioactive source and the scintillation crystal, the contact area between the radiating particles and the fluorescent layer is increased, improving the utilization efficiency of decaying particles. While effectively collecting decaying particles, the reflective structure enables the directional emission of photons, enhancing the light power density emitted from the side of the radiofluorescent module and improving the energy conversion efficiency of the radiofluorescent isotope solar cell.

Description

Technical Field

[0001] This invention relates to the field of micro energy, and more particularly to a highly efficient radiofluorescent isotope battery. Background Technology

[0002] Isotope batteries, also known as nuclear batteries, are battery devices that convert the energy-carrying particles or decay heat generated by the decay of a radioactive isotope source into electrical output through a transducer. Due to their unique advantages such as high energy density, stable energy source, and sustainable self-powering, they have far-reaching application prospects in special fields such as aerospace, military defense, and extreme environments.

[0003] In March 1896, Henri Becquerel observed radiofluorescence produced by the naturally occurring radioactive potassium diurethane sulfate, thus demonstrating for the first time the feasibility of converting radiation energy into light energy. In 1957, Elgin-Kidde... 147 A self-luminescent source was prepared by mixing a Pm source with CdS phosphor, and then a Si photovoltaic unit was used to transpose it, thus creating the first radio-induced photovoltaic isotope battery. This is a nuclear battery with an indirect energy conversion mechanism. It utilizes the energy-carrying particles generated by the decay of a radioactive isotope source to irradiate the phosphor layer, exciting radiofluorescent photons, which are ultimately collected by the photovoltaic unit to form electrical output.

[0004] In 2017, Johnny Russo and others from the U.S. Army Laboratory and the University of Maryland used... 63 A three-dimensional coupled radioluminescent isotope battery was fabricated by coupling an InGaP photovoltaic unit with a mixture of NiCl2 and ZnS:Cu,Al phosphor (Russo J, Litz M, Ray W, et al. A radioluminescent nuclear battery using volumetric configuration: 63Ni solution / ZnS:Cu,Al / InGaP[J].Applied Radiation and Isotopes,2017,130:66-74.), reducing the loss of isotope source energy; In 2021, the team led by Tang Xiaobin of Nanjing University of Aeronautics and Astronautics demonstrated the influence of radiation fluorescence intensity on the energy conversion efficiency of photovoltaic units (photovoltaic units have an incident light intensity threshold; when the incident light intensity is lower than this value, the photoelectric energy conversion efficiency is low), and proposed a scheme to improve the overall energy conversion efficiency of nuclear batteries by increasing the source term energy and activity (Jiang T,Xu Z,Meng C,et al.In-Depth Analysis of the Internal Energy Conversion of Nuclear Batteries and Radiation Degradation of Key Materials[J].Energy Technology,2020,8(12):2000667.). At present, the energy conversion efficiency of radiation fluorescence isotope batteries is generally less than 1%, which is significantly lower than the theoretically calculated energy conversion efficiency.

[0005] Currently developed radioluminescent isotope solar cells generally employ a simple three-layer structure: a radioactive source, a fluorescent layer, and a photovoltaic unit arranged sequentially. This structure has several disadvantages: source particles are emitted from only one side, leaving nearly half of the decaying particles unused; the phosphor material in the fluorescent layer has a large particle size, which, in addition to its own absorption, also blocks the emitted photons; and the photovoltaic unit only receives fluorescent photons generated by the isotope source per unit area, without employing optimized focusing technology to increase the emitted light power density, thus hindering the photoelectric energy conversion process. Therefore, existing radioluminescent isotope solar cells suffer from severe energy loss, low conversion efficiency, and weak output power, making it difficult to meet practical electricity demands. Summary of the Invention

[0006] The purpose of this invention is to solve the aforementioned problems in the prior art and provide a high-efficiency radioluminescent isotope battery. It is fabricated using micro / nano structures on the surface of a scintillation crystal, enabling directional emission of radioluminescent photons generated in the crystal from the side, thus enhancing the output power density per unit area. By employing a periodic arrangement of the radioactive source and the fluorescent layer, combined with the characteristic that isotope source decay particles exit at any angle, the loss of radiation energy is effectively reduced. This achieves improved source term efficiency, dense loading of the isotope source, and enhanced radioluminescent power density, resulting in a radioluminescent isotope battery with high transduction efficiency and strong output power.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-efficiency radiofluorescent isotope battery includes a transparent encapsulated waveguide, a radioisotope source, a radiofluorescent crystal, a reflective layer, an optical antireflection layer, a photovoltaic unit, and an optical coupling layer.

[0009] The transparent encapsulated waveguide is a hollow hexahedral structure. The optical antireflection layer is prepared inside the four light-emitting surfaces of the transparent encapsulated waveguide. The reflective layer is provided on the upper and lower surfaces of the radioluminescent crystal. The radioactive isotope source and the radioluminescent crystal are stacked alternately in the transparent encapsulated waveguide to form a radioluminescent component. The uppermost and lowermost layers of the transparent encapsulated waveguide are both radioluminescent crystals with reflective layers. The radioluminescent component and the photovoltaic unit are connected through an optical coupling layer to form a radioluminescent isotope cell.

[0010] The thickness of the radioactive isotope source does not exceed 500 μm, and the decay particles are emitted bidirectionally; the radioactive isotope source includes a solid sheet source, a liquid source, or a gel source.

[0011] The radioluminescent crystal is a hexahedral scintillation crystal and is in the form of thin sheets.

[0012] The photon transmittance of the radioluminescent crystal is not less than 80% at its emission wavelength, its length and width are consistent with the radioactive isotope source, and its height does not exceed the energy deposition depth of the radioactive isotope source decay particles in the radioluminescent crystal.

[0013] The four light-emitting surfaces of the radioluminescent crystal are roughened, including at least one of cutting, coarse grinding, fine grinding, and polishing.

[0014] The reflective layer is grown on the surface of a radioluminescent crystal using magnetron sputtering, electron beam evaporation, ion beam sputtering, atomic layer deposition, or molecular beam epitaxy.

[0015] The reflective layer is a metal thin film with a thickness of 50-100 nm, or a multilayer dielectric reflective film of TiO2 / SiO2 material with a thickness of less than 1 μm.

[0016] The transmittance of the transparent encapsulated waveguide is not less than 95%.

[0017] The thickness of the optical antireflective layer is 50 nm to 100 μm.

[0018] The quantum efficiency response curve of the photovoltaic unit covers the entire radioluminescence spectrum.

[0019] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0020] 1. By adopting a coupling method of fluorescent layer sandwiching radioactive source, the self-absorption of source term radiation energy is reduced, decay particles emitted from all directions are effectively collected, the specific surface area of ​​radioluminescence reaction per unit volume is increased, the loading activity of source term per unit volume is effectively increased, and higher energy density of isotope battery is achieved.

[0021] 2. Micro- and nano-fabrication is performed on the surface of the scintillation crystal to prepare a metal reflective film with a thickness of hundreds of nanometers and a multilayer dielectric film with a thickness of micrometers. This ensures minimal absorption of radiation particle energy and enables directional emission of fluorescent photons. Furthermore, by stacking multiple layers, the output light power density per unit area is greatly improved, so that the intensity of the radiative fluorescence light incident on the photovoltaic unit is higher than the incident light intensity threshold of the photovoltaic unit, thereby improving the overall energy conversion efficiency of the isotope cell.

[0022] 3. The types of radioactive isotope source terms required by this invention are extensive, including solid, liquid and gel states. Therefore, the source terms can be collected and obtained through various means, including radioactive nuclear waste, thereby reducing the production cost of isotope batteries from the source.

[0023] 4. The radioluminescent module and the photovoltaic unit in this invention are two independent components that can be separated and do not interfere with each other, which improves the reliability and convenience of the battery. In addition, the radioluminescent module can also be used alone as a long-life and highly reliable light source.

[0024] 5. The isotope battery described in this invention has a compact structure, small size, is safe and reliable, and has stable performance; it can achieve high power output through multi-module array integration and is expected to be more widely used in the future. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the radioactive isotope battery in this invention.

[0026] Figure 2 This is a top view schematic diagram of the radioactive fluorescent isotope battery in this invention.

[0027] Figure 3 This is a cross-sectional schematic diagram of the radioluminescent crystal in this invention.

[0028] Figure 4 This is a schematic diagram of a traditional radiofluorescent isotope battery.

[0029] Figure 5 The electrical output of the photovoltaic unit is shown in two different structures.

[0030] Figure reference numerals: 1-Transparent encapsulated waveguide; 2-Radioactive isotope source; 3-Radioactive fluorescent crystal; 4-Reflective layer; 5-Optical antireflection layer; 6-Photovoltaic unit; 7-Optical coupling layer. Detailed Implementation

[0031] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0032] like Figures 1-3 As shown, the radioactive fluorescent isotope battery of the present invention includes a transparent encapsulated waveguide 1, a radioactive isotope source 2, a radioactive fluorescent crystal 3, a reflective layer 4, an optical anti-reflection layer 5, a photovoltaic unit 6, and an optical coupling layer 7.

[0033] The transparent encapsulated waveguide 1 is a hollow hexahedral structure. The optical antireflection layer 5 is prepared inside the four light-emitting surfaces of the transparent encapsulated waveguide 1. The reflective layer 4 is provided on the upper and lower surfaces of the radioluminescent crystal 3. The radioactive isotope source 2 and the radioluminescent crystal 3 are stacked alternately in the transparent encapsulated waveguide 1 to form a radioluminescent component. The uppermost and lowermost layers of the transparent encapsulated waveguide 1 are both reflective layers 4 of the radioluminescent crystal 3. The radioluminescent component and the photovoltaic unit 5 are connected through the optical coupling layer 7 to form a radioluminescent isotope cell.

[0034] The radioactive isotope source includes, but is not limited to, tritium-3, nickel-63, strontium-90, promethium-147, and americium-241; the thickness of the radioactive isotope source does not exceed 500 μm, and the decay particles are emitted bidirectionally; the radioactive isotope source is a solid sheet source, a liquid source, or a gel source.

[0035] The radioluminescent crystal is a hexahedral scintillation crystal in the form of a thin sheet. Specifically, the radioluminescent crystal includes, but is not limited to, scintillation crystals made of materials such as YAG:Ce, GAGG:Ce, LuAG:Ce, LuAG:Pr, LYSO, LSO, BGO, CsI:Na, CsI:Tl, and NaI:Tl, as well as fluorescent layers made of common metal and rare earth doped fluorescent materials such as ZnS-based materials.

[0036] The photon transmittance of the radioluminescent crystal is not less than 80% at its emission wavelength, its length and width are consistent with the radioactive isotope source, and its height does not exceed the energy deposition depth of the radioactive isotope source decay particles in the radioluminescent crystal.

[0037] The upper and lower surfaces of the radioluminescent crystal are respectively prepared with reflective layers, and the remaining four light-emitting sides are roughened, including cutting the cross-section, coarse grinding, fine grinding, polishing, etc., which can enhance photon emission.

[0038] The reflective layer is grown on the surface of a radioluminescent crystal using processes such as magnetron sputtering, electron beam evaporation, ion beam sputtering, atomic layer deposition, or molecular beam epitaxy.

[0039] The reflective layer is a metal thin film such as Al or Ag with a thickness of 50-100 nm, or a multilayer dielectric reflective film of TiO2 / SiO2 material with a thickness of less than 1 μm.

[0040] The transparent encapsulated waveguide has a transmittance of not less than 95%, and its material is a high-transmittance, radiation-resistant material doped with lead, boron, etc., such as quartz glass.

[0041] The thickness of the optical antireflective layer is 50 nm to 100 μm.

[0042] The quantum efficiency response curve of the photovoltaic unit covers the entire radioluminescence spectrum, such as GaAs, Si, InP, InGaP, InGaAs, AlInP and other semiconductor photovoltaic units.

[0043] The optical coupling layer is made of materials such as optical silicone grease or high-transmission gel, which fills the space between the photovoltaic unit and the radioluminescent component, thereby reducing photon energy loss at the photon transport interface.

[0044] Example 1

[0045] The radioactive isotope battery in this embodiment was prepared by the following method:

[0046] 1) Select a thin sheet of YAG:Ce scintillation crystal, polish all six surfaces, and block four sides. Use magnetron sputtering to sputter Ag reflective layers on the upper and lower surfaces respectively, with a thickness of 50nm, to form good mirror reflection.

[0047] 2) The four light-emitting sides of the scintillator crystal without sputtered reflective layers are finely ground to achieve a surface roughness of approximately 2 μm;

[0048] 3) An optical antireflection layer is fabricated inside a transparent encapsulated waveguide using ion beam sputtering;

[0049] 4) Select a sheet-shaped radioactive isotope source with the same length and width as the scintillation crystal, and place it and the scintillation crystal alternately inside the transparent encapsulated waveguide. The bottom and top layers inside the transparent encapsulated waveguide are scintillation crystals, and the internal space of the transparent encapsulated waveguide is completely filled with no movable gaps.

[0050] 5) The transparent encapsulated waveguide filled with radioactive isotope source and scintillation crystal is bonded and encapsulated to form a complete radioluminescence component;

[0051] 6) Attach the InGaP photovoltaic unit to the four light-emitting sides of the radioluminescent module, fill the middle with optical grease to fix it, and lead out the electrode wires of the photovoltaic unit. At this point, the radioluminescent isotope cell of the present invention is completed.

[0052] By connecting the electrodes of the battery to electrical devices or energy storage capacitors, power can be supplied to the devices or energy can be stored.

[0053] Comparative Example 1

[0054] like Figure 4 As shown, Comparative Example 1 is a conventional radioluminescent isotope cell. The light received by a unit area photovoltaic cell is emitted by a unit area scintillation crystal excited by a unit area isotope source. The scintillation crystal (without a reflective layer on its surface), radioactive isotope source, and photovoltaic cell materials used in the fabrication of Comparative Example 1 are the same as those in Example 1, except for the structure. The conventional structure uses a front-facing light emission method.

[0055] According to the literature Jiang T, Xu Z, Meng C, et al. In-Depth Analysis of the Internal Energy Conversion of Nuclear Batteries and Radiation Degradation of Key Materials[J]. Energy Technology, 2020, 8(12): 2000667, it can be seen that the fluorescence emission intensity per unit area greatly affects the conversion efficiency of the photovoltaic unit, thus limiting the improvement of the overall energy conversion efficiency of the radioluminescent isotope cell. The structure proposed in this invention adopts a multi-layer close-packed coupling method between the radioactive isotope source and the scintillation crystal. The radioactive isotope source emission particles are excited on the large-size surface of the crystal, and the generated radioluminescence is realized by the reflection layer and the anti-reflection layer, so that photons are emitted from the four small-size sides. This increases the reaction cross section between the source term particles and the crystal, improves the source term loading activity, and effectively utilizes the decay particles emitted from the isotope source term at the 4π angle. This not only enhances the utilization efficiency of the source term, but also increases the emission power density per unit area in the radioluminescence module, achieving a higher photoelectric conversion efficiency.

[0056] Experiments were conducted to test the radiation fluorescence power density of the conventional structure and the high-efficiency transducer radiation fluorescence isotope cell proposed in this invention, as well as the electrical output parameters of the photovoltaic unit (see Table 1). Figure 5 The IV curves of the photovoltaic unit output tested under two different structures are shown. The structural dimensions of the scintillation crystal are 25mm×25mm×2mm, and the photon incident surface size of the photovoltaic unit is 25mm×25mm.

[0057] As shown in Table 1, the light output per unit area of ​​the structure of this invention increases by 77.6% compared to the traditional structure. The enhancement of radiofluorescence intensity is most directly reflected in the short-circuit current data of the photovoltaic unit, where the short-circuit current increases by 110%. In addition, the higher light intensity enhances the open-circuit voltage and fill factor of the photovoltaic unit, ultimately achieving higher output power. The photoelectric conversion efficiency of the photovoltaic unit in the traditional structure is only 5.99%, while the structure of this invention achieves higher light input to the photovoltaic unit surface, resulting in a photoelectric efficiency of 11.2%. This exhibits the same photovoltaic unit efficiency trend as mentioned in the literature above.

[0058] Table 1 Optical and electrical performance parameters of the traditional structure and the structure of this invention.

[0059]

[0060] The above description and examples are merely illustrative of the invention and should not be construed as limiting the specific implementation of the invention to these descriptions. Several simple deductions and modifications can be made without departing from the concept of the invention, and all should be considered within the scope of protection of the invention.

Claims

1. A high-efficiency radiofluorescent isotope battery, characterized in that: It includes a transparent encapsulated waveguide, a radioactive isotope source, a radioactive fluorescent crystal, a reflective layer, an optical antireflective layer, a photovoltaic unit, and an optical coupling layer; The transparent encapsulated waveguide is a hollow hexahedral structure. The optical antireflection layer is prepared inside the four light-emitting surfaces of the transparent encapsulated waveguide. The reflective layer is provided on the upper and lower surfaces of the radioluminescent crystal. The radioactive isotope source and the radioluminescent crystal are stacked alternately in the transparent encapsulated waveguide to form a radioluminescent component. The uppermost and lowermost layers of the transparent encapsulated waveguide are both reflective layers of the radioluminescent crystal. The radioluminescent component and the photovoltaic unit are connected through an optical coupling layer to form a radioluminescent isotope cell. The photovoltaic unit is located on the four light-emitting sides of the radioluminescent component.

2. The high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The thickness of the radioactive isotope source does not exceed 500 μm, and the decay particles are emitted bidirectionally; the radioactive isotope source includes a solid sheet source, a liquid source, or a gel source.

3. The high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The radioluminescent crystal is a hexahedral scintillation crystal and is in the form of thin sheets.

4. The high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The photon transmittance of the radioluminescent crystal is not less than 80% at its emission wavelength, its length and width are consistent with the radioactive isotope source, and its height does not exceed the energy deposition depth of the radioactive isotope source decay particles in the radioluminescent crystal.

5. The high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The four light-emitting surfaces of the radioluminescent crystal are roughened, including at least one of cutting, coarse grinding, fine grinding, and polishing.

6. The high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The reflective layer is grown on the surface of a radioluminescent crystal using magnetron sputtering, electron beam evaporation, ion beam sputtering, atomic layer deposition, or molecular beam epitaxy.

7. A high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The reflective layer is a metal thin film with a thickness of 50~100 nm, or a multilayer dielectric reflective film of TiO2 / SiO2 material with a thickness of less than 1 μm.

8. The high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The transmittance of the transparent encapsulated waveguide is not less than 95%.

9. A high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The thickness of the optical antireflective layer is 50 nm to 100 μm.

10. A high-efficiency radiofluorescent isotope battery as described in claim 1, characterized in that: The quantum efficiency response curve of the photovoltaic unit covers the entire radioluminescence spectrum.

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