Atomic battery

Abstract

The present application provides an atomic battery that is lightweight and thin. The present application solves the above problem by providing an atomic battery that includes a thermoelectric conversion element having a thermoelectric conversion portion exhibiting nonreciprocal conduction based on a broken spatial inversion symmetry and a pair of electrodes disposed apart from each other in the thermoelectric conversion portion and used to extract a nonreciprocal thermoelectric signal, and at least one structural component of the atomic battery contains a radioisotope element.

Description

Technical Field

[0001] This invention relates to an atomic energy battery that extracts electrical energy from decay heat by containing radioactive isotopes. Background Technology

[0002] Even after use, the fuel used in nuclear power generation contains radioactive isotopes and continues to release heat from nuclear decay, making its long-term management an extremely important issue. If a method can be cleverly developed to convert this heat energy into electricity, it can be considered an extremely stable power source capable of long-term operation. In fact, deep space probes that cannot use solar power carry isotope batteries composed of radioactive isotopes and thermoelectric elements, supporting long-term missions for decades and still continuously transmitting deep space images back to Earth.

[0003] As a traditional technology, a radioisotope thermoelectric generator (RTG) is used. This generator extracts electricity from radioactive decay. By using thermocouples, the Seebeck effect is utilized to convert the decay heat of radioactive materials into electrical energy.

[0004] For example, Patent Document 1 discloses an atomic energy battery that exhibits less radiation-induced aging and can be miniaturized.

[0005] [Existing Technical Documents]

[0006] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2021-85774 Summary of the Invention

[0008] [The problem the invention aims to solve]

[0009] The atomic battery disclosed in Patent Document 1 requires cooling due to its use of temperature gradients, resulting in a bulky device. Therefore, there is a demand for further lightweighting and thin-film construction.

[0010] This disclosure was made in view of the above circumstances, and its object is to provide an atomic energy battery that can be made lightweight and thin-film.

[0011] [Methods for solving the problem]

[0012] After in-depth research, the inventors discovered that by providing a thermoelectric conversion element comprising: a thermoelectric conversion section exhibiting non-reciprocal conduction based on spatial inversion symmetry breaking; and a pair of electrodes spaced apart from the thermoelectric conversion section for extracting non-reciprocal thermoelectric signals, a thermoelectric conversion element capable of thermoelectric conversion from temperature fluctuations at the microscale can be provided. Furthermore, by including a radioactive isotope in at least one structural component constituting the atomic battery within an atomic battery equipped with this thermoelectric conversion element, a lightweight and thin-film atomic battery can be conceived.

[0013] That is, one embodiment of this disclosure relates to an atomic energy battery, characterized in that it is an atomic energy battery containing a thermoelectric conversion element, said thermoelectric conversion element comprising: a thermoelectric conversion section exhibiting non-reciprocal conduction based on the breaking of spatial inversion symmetry, and,

[0014] A pair of electrodes, spaced apart from each other, are disposed in the aforementioned thermoelectric conversion unit and are used to extract non-reciprocal thermoelectric signals.

[0015] At least one structural component constituting the atomic battery contains a radioactive isotope element.

[0016] In this disclosure, the following embodiment is preferred: the thermoelectric conversion section is a thermoelectric conversion layer comprising mutually stacked ferromagnetic metal layers and paramagnetic metal layers, and the pair of electrodes are disposed on the thermoelectric conversion layer at intervals in the in-plane direction of the thermoelectric conversion layer. Therefore, the voltage of the thermoelectric conversion based on the broken spatial inversion symmetry of the thermoelectric conversion layer increases, and thus the power generation efficiency of the nuclear battery becomes particularly high.

[0017] In this disclosure, the preferred embodiment is one where the distance between the pair of electrodes is 0.1 μm or more and 1000 μm or less. By setting the distance within this range, the thermoelectric conversion voltage increases, thereby improving the power generation efficiency of the nuclear battery.

[0018] In this disclosure, the following embodiments are preferred: the paramagnetic metal layer is composed of a single layer or multiple stacked layers, wherein the single layer or multiple stacked layers of the paramagnetic metal layer are respectively composed of Pt, Pd, W, AuW alloy, Ta, CuIr alloy, CuBi alloy, BiSb alloy, or BiSe alloy. Therefore, the non-reciprocity of the conduction based on the breaking of spatial inversion symmetry in the thermoelectric conversion layer becomes particularly large, thus the power generation efficiency of the nuclear battery becomes particularly high.

[0019] In this disclosure, the following embodiments are preferred: the ferromagnetic metal layer is composed of a single layer or multiple layers stacked together, and each of the single layer or multiple layers of the ferromagnetic metal layer is composed of a Ni-Fe alloy, Fe, Co, Ni, Gd, CoFeB alloy, or (Ga,Fe)Sb alloy. These are materials that exhibit ferromagnetism at room temperature and can achieve non-reciprocal conductivity at room temperature, thus improving the power generation efficiency of the nuclear power cell.

[0020] In this disclosure, the following embodiments are preferred: the aforementioned radioactive isotopes comprise elements selected from beryllium-10, carbon-14, aluminum-26, silicon-32, chlorine-36, argon-39, potassium-40, nickel-63, selenium-79, rubidium-87, zirconium-93, indium-115, cesium-137, lanthanum-138, niobium-94, technetium-98, lutetium-71, neodymium-144, samarium-146, samarium-147, and gadolinium-152. At least one element from the group consisting of Platinum-190, Bismuth-210, Polonium-209, Thorium-232, Uranium-232, Uranium-233, Uranium-234, Uranium-235, Uranium-236, Uranium-238, Plutonium-236, Plutonium-238, Plutonium-239, Plutonium-244, Americium-241, Americium-243, Curium-244, Curium-246, Curium-247, Curium-248, Californium-249, and Californium-251. By using these radioactive isotopes, the power generation efficiency of atomic batteries becomes exceptionally high.

[0021] Another embodiment of this disclosure is an atomic energy battery module comprising a plurality of atomic energy batteries as described above, wherein the plurality of atomic energy batteries are electrically connected to each other in a manner that superimposes non-reciprocal thermoelectric signals from each atomic energy battery in the same polarity. This allows for the extraction of a larger non-reciprocal thermoelectric signal, thereby improving the power generation efficiency of the atomic energy batteries.

[0022] [Invention Effects]

[0023] According to this disclosure, a lightweight and thin-film atomic energy battery can be provided.

[0024] According to the thermoelectric conversion element of the atomic energy cell disclosed herein, the thermoelectric signal generated in the thermoelectric conversion section based on the incoming heat flow exhibits non-reciprocity with respect to the direction of the heat flow due to the non-reciprocal conduction of the thermoelectric conversion section, and this non-reciprocal thermoelectric signal can be electrically extracted through a pair of electrodes.

[0025] More specifically, when heat flows into a stack of ferromagnetic and paramagnetic metal layers magnetized by a magnetic field of less than 1T, it drives a spin flow within the paramagnetic metal layer, forming a spin accumulation at the interface between the paramagnetic and ferromagnetic metal layers. The polarity of this spin accumulation is either parallel or antiparallel to the magnetization direction of the ferromagnetic metal layer, depending on the direction of the heat flow. Electron scattering changes according to the relative orientation between the polarity of this spin accumulation and the magnetization direction, resulting in a thermoelectric signal in the thermoelectric conversion layer that is dependent on the direction of the heat flow, i.e., non-reciprocal. This is a non-reciprocal thermoelectric signal, which can be electrically extracted through a pair of electrodes. Therefore, even with heat flow that varies randomly in direction and magnitude, a thermoelectric signal with a fixed direction can be generated within the paramagnetic metal layer, enabling thermoelectric conversion using temperature fluctuations at the microscale.

[0026] By using such a thermoelectric conversion element, a lightweight and thin-film atomic energy battery can be provided. Attached Figure Description

[0027] 【 Figure 1 The image shows a cross-sectional schematic diagram of one embodiment of an atomic energy battery.

[0028] 【 Figure 2 The image shows a cross-sectional schematic diagram of one embodiment of an atomic energy battery.

[0029] 【 Figure 3 This image shows a perspective view of the thermoelectric conversion element involved in the embodiment.

[0030] 【 Figure 4 Cross-sectional view of the thermoelectric conversion element involved in the implementation method.

[0031] 【 Figure 5 The diagram shows a process flow diagram of the thermoelectric conversion method according to the embodiment.

[0032] 【 Figure 6 This image shows a perspective view of the structure of a thermoelectric conversion module using thermoelectric conversion elements.

[0033] 【 Figure 7 [Schematic diagram of the atomic energy battery involved in the embodiment]

[0034] [Attached image labels]

[0035] 10, 20, 30: Atomic batteries

[0036] 11, 21, 31: Paramagnetic metal layers

[0037] 12, 22: Ferromagnetic metal layer

[0038] 13, 23: Thermoelectric conversion element

[0039] 14, 24: Electrodes

[0040] 25: Substrate

[0041] 16, 26, 36: Radioisotopes

[0042] 37: Hot

[0043] 38: Radiation

[0044] 200: Thermoelectric conversion element

[0045] 202: Thermoelectric conversion layer

[0046] 203: Ferromagnetic metal layer

[0047] 205: Paramagnetic metal layer

[0048] 207a, 207b: A pair of electrodes

[0049] 300: Thermoelectric conversion module. Detailed Implementation

[0050] Hereinafter, this specific embodiment will be described in detail with reference to the accompanying drawings. Furthermore, in each drawing, the same elements are used with the same symbols where possible. Also, for ease of observation of the drawings, the dimensional ratios within and between constituent elements are arbitrary.

[0051] One embodiment of this disclosure is an atomic energy battery containing a thermoelectric conversion element, the thermoelectric conversion element comprising: a thermoelectric conversion section exhibiting non-reciprocal conduction based on spatial inversion symmetry breaking, and a pair of electrodes disposed at intervals between the thermoelectric conversion section for extracting non-reciprocal thermoelectric signals.

[0052] <Thermoelectric Conversion Section>

[0053] The thermoelectric conversion unit is a thermoelectric conversion element that exhibits non-reciprocal conduction based on the breaking of spatial inversion symmetry. There are no particular limitations on the materials constituting the thermoelectric conversion unit, as long as they exhibit non-reciprocal conduction based on the breaking of spatial inversion symmetry; typically, they include stacks of ferromagnetic and paramagnetic metal layers.

[0054] In this stack, although a paramagnetic metal layer is disposed on one face of the ferromagnetic metal layer, the same paramagnetic metal layer is not disposed on the other face of the ferromagnetic metal layer. Furthermore, although a ferromagnetic metal layer is disposed on one face of the paramagnetic metal layer, the same ferromagnetic metal layer is not disposed on the other face of the paramagnetic metal layer. Therefore, the stack of mutually stacked ferromagnetic and paramagnetic metal layers has a structure with broken spatial inversion symmetry in its stacking direction. This stack substantially possesses spatial inversion symmetry in the in-plane direction. Moreover, due to the broken spatial inversion symmetry in this stacking direction, the stack exhibits non-reciprocity in its in-plane conductivity.

[0055] The ferromagnetic metal layer is composed of a metal that exhibits ferromagnetism at the operating temperature of the atomic energy battery. Preferably, it is composed of a metal that exhibits ferromagnetism at room temperature (around 300K), and for this purpose, it is preferably composed of Fe, Co, Ni, Gd, or an alloy containing at least one of them, and particularly preferably composed of a Ni-Fe alloy, Co, or CoFeB.

[0056] There are no particular limitations on the thickness of the ferromagnetic metal layer; for example, it can be set to more than 1 nm or less than 100 nm.

[0057] The paramagnetic metal layer is composed of a metal that exhibits paramagnetism at the operating temperature of the atomic energy battery, preferably a metal that exhibits paramagnetism at room temperature (around 300K). To enhance the spin Nernst effect within the paramagnetic metal layer (described later), the paramagnetic metal layer is preferably composed of a paramagnetic metal with high spin-orbit interaction. From this perspective, it is preferably composed of Pt, Pd, W, AuW alloys, Ta, CuIr alloys, CuBi alloys, BiSb alloys, or BiSe alloys, and particularly preferably Pt.

[0058] There are no particular limitations on the thickness of the paramagnetic metal layer; for example, it can be set to more than 1 nm or less than 100 nm.

[0059] <Electrode>

[0060] Electrodes are arranged at intervals on the thermoelectric conversion unit to extract non-reciprocal thermoelectric signals from the thermoelectric conversion unit. Their arrangement is not particularly limited as long as non-reciprocal thermoelectric signals from the thermoelectric conversion unit can be extracted; typically, they are arranged at intervals on the surface of the thermoelectric conversion unit.

[0061] When a pair of electrodes are arranged at intervals on the surface of the thermoelectric conversion section, the interval in the in-plane direction of the thermoelectric conversion section is preferably 0.1 μm or more and 1000 μm or less. Furthermore, the thickness of the electrodes is not particularly limited, and can be, for example, 10 nm or more and 1 μm or less.

[0062] The electrode is made of a material with conductivity that enables the extraction of non-reciprocal thermoelectric signals from the thermoelectric conversion layer. Examples of such materials include metallic materials such as Cu, Ag, Au, Pt, Ni, Al, constantan, Cr, In, Pd, Fe, Cu alloys, Ti / Au stacks, and Cr / Au stacks; conductive oxides such as indium tin oxide (ITO) and zinc oxide (ZnO); preferably Cu, Ag, Au, Pt, Ni, Al, constantan, and Cu alloys; and particularly preferably Cu, Au, Ag, Pt, Ni, Ti / Au stacks, and Cr / Au stacks.

[0063] <Substrate>

[0064] Atomic batteries can have a substrate supporting the thermoelectric conversion section. The shape of the substrate is not particularly limited; it can be plate-like or film-like. Furthermore, the material of the substrate is not particularly limited; for example, metals such as Au, Ag, Cu, and Al; silicon, sapphire, SiC, GaN, yttrium-stabilized zirconium oxide (YSZ); and resins such as polyimide, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN).

[0065] <Manufacturing Method of Thermoelectric Conversion Unit>

[0066] The thermoelectric conversion section is formed, for example, by the following method: A substrate is prepared; materials for forming a ferromagnetic metal layer and materials for forming a paramagnetic metal layer are sequentially deposited on the substrate surface using a physical vapor deposition method such as DC magnetron sputtering to form a laminate; the laminate is then patterned into a rectangular shape in a top view using photolithography and lift-off methods to form the thermoelectric conversion section. Next, metal materials for forming a pair of electrodes are deposited in the region including the surface of the paramagnetic metal layer using a physical vapor deposition method such as DC magnetron sputtering to form a metal layer; the metal layer is then patterned into a predetermined shape using photolithography and lift-off methods to form a pair of electrodes. Furthermore, the deposition order of the ferromagnetic metal layer and the paramagnetic metal layer formed on the substrate can be reversed. Alternatively, the metal layer that will become the electrode can be formed on the substrate first, followed by the deposition of the ferromagnetic metal layer and the paramagnetic metal layer.

[0067] In addition, the thermoelectric conversion section may also have a layer made of an insulating magnetic material that is disposed in contact with the ferromagnetic metal layer.

[0068] <Radioactive Isotope>

[0069] In the atomic energy battery disclosed herein, at least one structural component constituting the atomic energy battery contains a radioactive isotope. The radioactive isotope only needs to have the ability to emit radiation; examples include beryllium-10, carbon-14, aluminum-26, silicon-32, chlorine-36, argon-39, potassium-40, nickel-63, selenium-79, rubidium-87, zirconium-93, indium-115, cesium-137, lanthanum-138, niobium-94, technetium-98, lutetium-71, neodymium-144, samarium-146, samarium-147, and gadolinium-1. 52. Platinum-190, Bismuth-210, Polonium-209, Thorium-232, Uranium-232, Uranium-233, Uranium-234, Uranium-235, Uranium-236, Uranium-238, Plutonium-236, Plutonium-238, Plutonium-239, Plutonium-244, Americium-241, Americium-243, Curium-244, Curium-246, Curium-247, Curium-248, Californium-249, Californium-251, etc. Among these, Plutonium-238 and Curium-244 are preferred.

[0070] A radioactive isotope is contained in at least one structural component constituting an atomic battery. (Use) Figure 1 and Figure 2 Specific examples will be provided.

[0071] Figure 1 A cross-sectional schematic diagram of an atomic energy cell is shown, in which the structural components constituting the atomic energy cell are a thermoelectric conversion section composed of paramagnetic and ferromagnetic metal layers, and a pair of electrodes. Figure 1 In the nuclear battery 10, all structural components, namely the paramagnetic metal layer 11, the ferromagnetic metal layer 12, and a pair of electrodes 14, contain radioactive isotopes 16.

[0072] There are no particular limitations on the methods used to contain radioactive isotopes in structural components, and well-known methods may be used as appropriate. For example, methods such as injecting radioactive isotopes into structural components using an accelerator may be cited.

[0073] have Figure 1 In the atomic energy cell with the structural components shown, another example of the configuration of radioactive isotopes is:

[0074] • Only electrodes are equipped with radioactive isotopes

[0075] • Only the paramagnetic metal layer is equipped with radioactive isotopes

[0076] • Only the ferromagnetic metal layer is equipped with radioactive isotopes

[0077] • Electrodes and paramagnetic metal layers are equipped with radioactive isotopes

[0078] • Electrodes and ferromagnetic metal layers are equipped with radioactive isotopes

[0079] • Radioactive isotopes are arranged in the paramagnetic and ferromagnetic metal layers.

[0080] Figure 2 A cross-sectional schematic diagram of an atomic energy cell is shown, in which the structural components constituting the atomic energy cell are a thermoelectric conversion section composed of paramagnetic and ferromagnetic metal layers, a pair of electrodes, and a substrate. Figure 2 In the nuclear battery 20, all structural components, namely the paramagnetic metal layer 21, the ferromagnetic metal layer 22, the pair of electrodes 24 and the substrate 25, contain radioactive isotopes 26.

[0081] have Figure 2 In the atomic energy cell with the structural components shown, another example of the configuration of radioactive isotopes is:

[0082] • Only electrodes are equipped with radioactive isotopes

[0083] • Only the paramagnetic metal layer is equipped with radioactive isotopes

[0084] • Only the ferromagnetic metal layer is equipped with radioactive isotopes

[0085] • Only the substrate is equipped with radioactive isotopes

[0086] • Electrodes and paramagnetic metal layers are equipped with radioactive isotopes

[0087] • Electrodes and ferromagnetic metal layers are equipped with radioactive isotopes

[0088] • Electrodes and substrates are configured with radioactive isotopes

[0089] • Paramagnetic and ferromagnetic metal layers are configured with radioactive isotopes

[0090] • The paramagnetic metal layer and substrate are configured with radioactive isotopes

[0091] • Ferromagnetic metal layer and substrate with radioactive isotopes

[0092] • Radioactive isotopes are configured on the electrodes, paramagnetic metal layer, and ferromagnetic metal layer.

[0093] • Radioactive isotopes are configured on the electrodes, paramagnetic metal layer, and substrate.

[0094] • Radioactive isotopes are configured on the electrodes, ferromagnetic metal layer, and substrate.

[0095] • Radioactive isotopes are configured in the paramagnetic metal layer, the ferromagnetic metal layer, and the substrate.

[0096] As mentioned above, any structural component constituting an atomic battery can contain radioactive isotopes. This is based on the fact that the thermoelectric conversion unit of the atomic battery disclosed herein does not generate electricity through the spin Seebeck effect as disclosed in Patent Document 1, but rather through the spin Nernst effect as described below, thus eliminating the need for a temperature gradient relative to the thermoelectric conversion elements in the stacking direction.

[0097] Therefore, it is not necessary to use a configuration where the radioactive isotope element is only disposed on one side of the stacking direction of the thermoelectric conversion section. Specifically, it is not necessary to use a configuration where the thermoelectric conversion section, the substrate, and the radioactive isotope layer are stacked sequentially, nor is it necessary to use a configuration where the radioactive isotope layer, the thermoelectric conversion section, and the substrate are stacked sequentially.

[0098] Furthermore, there is no need to configure the radioactive isotope in a manner that generates a temperature gradient in the thermoelectric conversion section to induce the spin Seebeck effect.

[0099] Furthermore, in atomic batteries, multiple radioactive isotopes can be randomly arranged within structural components and / or across multiple components. That is, the radioactive isotopes do not need to be arranged in a form such as a radioactive isotope layer.

[0100] Next, the thermoelectric conversion method involved in this embodiment will be described. Figure 5 This is a process diagram illustrating the steps of the thermoelectric conversion method according to this embodiment. For example... Figure 5 As shown, the thermoelectric conversion method according to this embodiment includes the following steps: step S11 of preparing a thermoelectric conversion element; step S12 of inputting heat flow; and step S13 of performing thermoelectric conversion while applying an external magnetic field. For these steps, refer to... Figure 3 and Figure 4 At the same time, an explanation will be provided.

[0101] In step S11 of preparing the thermoelectric conversion element, the following is prepared: Figure 3 , Figure 4 The thermoelectric conversion element 200 is shown. Next, in the process of inputting heat flow S12, the heat flow H from the outside, which is the object of thermoelectric conversion, is input relative to the thermoelectric conversion layer 202 in such a way that the heat flow H flows along one of the X-axis directions (in the XY plane) of the thermoelectric conversion layer 202.

[0102] Then, in step S13, where thermoelectric conversion is performed simultaneously with the application of an external magnetic field, an external magnetic field B generated by a magnetic field generating unit disposed outside the thermoelectric conversion element 200 is applied to the ferromagnetic metal layer 203. The application direction of the external magnetic field B is set to an in-plane (XY plane) direction of the thermoelectric conversion element 200, and is the negative Y-axis direction on one side of the direction orthogonal to the flow direction of the heat flow H. As a result, the ferromagnetic metal layer 203 is magnetized in the direction of the external magnetic field B, having a magnetization 203M in the direction of the external magnetic field B. This external magnetic field B is maintained during the thermoelectric conversion of the heat flow H. The magnitude of the external magnetic field B can be, for example, set to 1T or less.

[0103] In process S13, when the heat flow H flows into the paramagnetic metal layer 205, a spin flow J is generated along the Z-axis direction. S And flow into the ferromagnetic metal layer 203. Spin flow J S The polarity of the heat flux J changes to either the positive or negative Y-axis direction depending on the direction of the heat flux H. Therefore, when the direction of the heat flux H is reversed, the spin flow J... S The polarity also reverses, and the spin flow J S The polarity of the magnetization J is also reversed relative to the orientation of the magnetization direction 203M of the ferromagnetic metal layer 203. Furthermore, by reversing the magnetization direction 203M of the ferromagnetic metal layer 203, the spin current J can also be... S The polarity of the magnetized 203M is reversed relative to its orientation.

[0104] Spin Flow J S When electrons flow into the ferromagnetic metal layer 203, electron scattering changes according to the relative orientation of the spin current's polarity direction and the magnetization direction 203M of the ferromagnetic metal layer 203. Since the spin current's polarity direction near the interface between the ferromagnetic metal layer 203 and the paramagnetic metal layer 205 changes according to the direction of the heat flow H, this electron scattering also changes according to the direction of the heat flow H. Therefore, the thermoelectric signal generated in the thermoelectric conversion layer 202 exhibits a dependence on the direction of the heat flow H, i.e., non-reciprocity.

[0105] The inventors discovered that, thereby, the thermoelectric signal J generated within the thermoelectric conversion layer 202 N In this process, due to the non-reciprocal conduction of the thermoelectric conversion layer 202 as described above, it exhibits non-reciprocity relative to the direction of heat flow H (i.e., the thermoelectric signal J...). N (The direction of the heat flux H varies non-linearly), regardless of whether the direction of the heat flux H is in the positive or negative X-axis direction, the thermoelectric signal J... N The directions of all signals are the positive X-axis direction, and such non-reciprocal thermoelectric signals J... NIt can be electrically extracted via a pair of electrodes 207a and 207b. Therefore, according to the thermoelectric conversion element 200 of this embodiment, even if the direction and magnitude of the heat flow H change randomly, a non-reciprocal thermoelectric signal J can be generated in a constant direction within the thermoelectric conversion layer 202. N Therefore, thermoelectric conversion can be achieved through temperature fluctuations at the microscopic scale.

[0106] Furthermore, by reversing the direction of the external magnetic field B to the positive Y-axis direction and reversing the direction of the magnetization 203M of the ferromagnetic metal layer 203 to the positive Y-axis direction, the non-reciprocal thermoelectric signal J can be converted. N The direction is reversed to the negative direction of the X-axis.

[0107] In the thermoelectric conversion layer 202, the non-reciprocal thermoelectric signal J extracted through a pair of electrodes 207a and 207b is... N Let the magnitude of the voltage be V, the electric field generated in the thermoelectric conversion layer 202 corresponding to V be E, the nonlinear Seebeck coefficient of the thermoelectric conversion layer 202 be S, and the distance between a pair of electrodes 207a and 207b be L. Figure 4 When the temperature gradient of the thermoelectric conversion layer 202 within a distance L is set as ∇T, and the temperature difference of the thermoelectric conversion layer 202 within a distance L is set as ΔT, the electric field E = nonlinear Seebeck coefficient S × (temperature gradient ∇T). 2 The relationship holds. By multiplying both sides of this equation by the distance L, we obtain the voltage V = nonlinear Seebeck coefficient S × (temperature difference ΔT). 2 / L, therefore, the smaller the distance L between the pair of electrodes 207a and 207b, the larger the voltage V. Thus, as described above, by preferably setting the spacing D207 along the X-axis direction between the pair of electrodes 207a and 207b to a value as small as 1000 μm or less, the non-reciprocal thermoelectric signal J extracted through the pair of electrodes 207a and 207b... N Increase.

[0108] Furthermore, the thermoelectric conversion element 200 may also include a heat conduction section, which is disposed in contact with or close to the end face on the positive side of the X-axis and / or the end face on the negative side of the X-axis, and is used to facilitate the flow of heat H into the thermoelectric conversion layer 202. Such a heat conduction section may be made of, for example, aluminum, copper, carbon fiber, sapphire, alumina, silicon with a thermal oxide film, or a polymer.

[0109] Figure 6 This is a perspective view showing the configuration of a thermoelectric conversion module using the thermoelectric conversion element described above. Figure 6As shown, the thermoelectric conversion module 300 of this embodiment includes multiple thermoelectric conversion elements 200. In this embodiment, it has four thermoelectric conversion elements 200a, 200b, 200c, and 200d. These four thermoelectric conversion elements 200a, 200b, 200c, and 200d enable the non-reciprocal thermoelectric signal J from each thermoelectric conversion element to... N They are electrically connected to each other in a manner that combines the same polarity.

[0110] Specifically, in the thermoelectric conversion module 300, in conjunction with... Figure 3 and Figure 4 The thermoelectric conversion elements 200a and 200c shown are arranged in the same manner relative to the Cartesian coordinate system C as the thermoelectric conversion elements 200a and 200c. Figure 3 and Figure 4 The thermoelectric conversion elements 200 shown are arranged with respect to Cartesian coordinate system C, rotated 180 degrees around the Y-axis, and alternatingly along the Y-axis direction with respect to thermoelectric conversion elements 200b and 200d. Furthermore, the electrode 207a of thermoelectric conversion element 200a is electrically connected to the electrode 207b of thermoelectric conversion element 200b, the electrode 207a of thermoelectric conversion element 200b is electrically connected to the electrode 207b of thermoelectric conversion element 200c, and the electrode 207a of thermoelectric conversion element 200c is electrically connected to the electrode 207b of thermoelectric conversion element 200d. Alternatively, instead of arranging thermoelectric conversion elements 200b and 200d in a manner rotated 180 degrees around the Y-axis, the thermoelectric conversion elements 200b and 200d can be arranged similarly to thermoelectric conversion elements 200a and 200c. Figure 3 and Figure 4 The thermoelectric conversion element 200 shown is similarly configured relative to the Cartesian coordinate system C. In thermoelectric conversion elements 200b and 200d, the stacking order of the ferromagnetic metal layer 203 and the paramagnetic metal layer 205 of the thermoelectric conversion layer 202 is reversed. In this case, the electrode 207a of thermoelectric conversion element 200a is electrically connected to the electrode 207a of thermoelectric conversion element 200b, the electrode 207b of thermoelectric conversion element 200b is electrically connected to the electrode 207b of thermoelectric conversion element 200c, and the electrode 207a of thermoelectric conversion element 200c is electrically connected to the electrode 207a of thermoelectric conversion element 200d.

[0111] Furthermore, through an external magnetic field B, the ferromagnetic metal layers 203 of each of the four thermoelectric conversion elements 200a, 200b, 200c, and 200d are all magnetized along the negative Y-axis, thus having a magnetization 203M oriented toward the negative Y-axis.

[0112] Furthermore, the thermoelectric conversion module 300 includes heat conduction sections 301 and 302, which are disposed in contact with or close to the negative and positive X-axis end faces of the four thermoelectric conversion elements 200a, 200b, 200c, and 200d. This allows heat flowing along the X-axis to easily enter the ferromagnetic metal layer 203 of each of the four thermoelectric conversion elements 200a, 200b, 200c, and 200d. The thermoelectric conversion module 300 may also omit the heat conduction sections 301 and 302.

[0113] Heat flows into the ferromagnetic metal layer 203 of each of the four thermoelectric conversion elements 200a, 200b, 200c, and 200d. The non-reciprocal thermoelectric signals generated in each thermoelectric conversion element 200 are superimposed with the same polarity and can be extracted through the electrode 207b of thermoelectric conversion element 200a and the electrode 207a of thermoelectric conversion element 200d. Therefore, a larger non-reciprocal thermoelectric signal can be extracted.

[0114] Furthermore, atomic batteries can also have a shield composed of radiation-shielding components. The purpose of the shield is to prevent radiation emitted from radioactive isotopes from being released into the external environment; therefore, it can be the outermost layer of the atomic battery or a casing covering the battery. Similarly, atomic battery modules can also have a shield.

[0115] As a shielding body, known radiation shielding components can be used, including typical radiation shielding components such as lead and concrete, as well as rubber sheets or resin sheets with radiation shielding capabilities.

[0116] The thermoelectric conversion element in a nuclear battery can be single-layered, or it can be multilayered to obtain a larger electromotive force. Furthermore, a protective film can be provided to protect the thermoelectric conversion element, and the nuclear battery can be connected to terminals and used as a nuclear battery element.

[0117] Furthermore, the size and shape of the atomic battery can be customized to suit the intended use.

[0118] The atomic energy battery of this disclosure has been described in detail above, but the scope of the invention is not limited to the foregoing examples. Various modifications or alterations may be made without departing from its spirit.

[0119] For example, in the above embodiment, in step S13, an external magnetic field B is applied to the ferromagnetic metal layer 203 in a direction orthogonal to the flow direction of the heat flow H, along the in-plane (XY plane) direction of the thermoelectric conversion element 200. Figure 3 and Figure 4However, it can also be applied along the in-plane (XY plane) direction of the thermoelectric conversion element 200, intersecting the flow direction of the heat flow H at an angle other than 90 degrees. However, the external magnetic field B and the heat flow H are set to avoid being parallel or antiparallel to each other.

[0120] Furthermore, in the above-described embodiments, in step S13, thermoelectric conversion is performed simultaneously with the application of an external magnetic field B (see reference). Figure 3 and Figure 4 If the ferromagnetic metal layer 203 can be magnetized 203M without the application of an external magnetic field B, then thermoelectric conversion can be performed in step S13 without the application of an external magnetic field B. As a method to achieve this, for example, the following methods can be used: the ferromagnetic metal layer 203 is made of a material with high coercivity, and the ferromagnetic metal layer 203 has a magnetization 203M as remanence; and a layer or component is provided on the thermoelectric conversion element 200 to apply a static magnetic field or an exchange-coupled magnetic field to the ferromagnetic metal layer 203. For example, in order to apply an exchange-coupled magnetic field to the ferromagnetic metal layer 203, the thermoelectric conversion element 200 may further include antiferromagnetic layers such as NiO, IrMn, FeMn, NiMn, PtMn, PdMn, Mn2Au, FeRh, and MnSb stacked on the opposite side of the paramagnetic metal layer 205 side of the ferromagnetic metal layer 203. Thus, thermoelectric conversion can be performed without the application of an external magnetic field B.

[0121] Furthermore, in the above embodiments, a pair of electrodes 207a and 207b are disposed on the upper surface 205S of the paramagnetic metal layer 205 in a manner that is not in contact with the ferromagnetic metal layer 203 and is spaced apart from each other along the X-axis (see reference). Figure 3 and Figure 4 However, it can also be disposed on the sides of the paramagnetic metal layer 205 in the positive and negative directions of the X-axis, respectively, in a manner that is not in contact with the ferromagnetic metal layer 203 and is spaced apart from each other along the X-axis.

[0122] Furthermore, in the above embodiments, the ferromagnetic metal layer 203 is a single layer (see reference). Figure 3 and Figure 4However, the ferromagnetic metal layer 203 can also be composed of multiple stacked ferromagnetic metal layers. In this case, preferably, these multiple layers are composed of Ni-Fe alloy, Fe, Co, Ni, Gd, CoFeB alloy or (Ga,Fe)Sb alloy, respectively. Such a stacked multiple ferromagnetic metal layer can, for example, be a stack formed by periodically stacking layers composed of multiple ferromagnetic metals (for example, when the layer composed of the first ferromagnetic metal is layer A, the layer composed of the second ferromagnetic metal is layer B and the layer composed of the third ferromagnetic metal is layer C, such as a stack formed by periodically stacking three types of layers A, B, C, A, B, C...); or a stack formed by randomly stacking layers composed of multiple ferromagnetic metals (for example, a stack formed by randomly stacking three types of layers A, B, C, B, A, C...).

[0123] Furthermore, in the above embodiments, the paramagnetic metal layer 205 is a single layer (see reference). Figure 3 and Figure 4 However, the paramagnetic metal layer 205 can also be composed of multiple stacked paramagnetic metal layers. In this case, preferably, these multiple layers are composed of Pt, Pd, W, AuW alloy, Ta, CuIr alloy, CuBi alloy, BiSb alloy, or BiSe alloy, respectively. As such a stacked multiple paramagnetic metal layer, for example, it can be a stack formed by periodically stacking layers composed of multiple paramagnetic metals (for example, when the layer composed of the first paramagnetic metal is layer D, the layer composed of the second paramagnetic metal is layer E, and the layer composed of the third paramagnetic metal is layer F, such as a stack formed by periodically stacking three layers such as layer D, layer E, layer F, layer D, layer E, layer F...); or a stack formed by randomly stacking layers composed of multiple paramagnetic metals (for example, a stack formed by randomly stacking three layers such as layer D, layer E, layer F, layer E, layer D, layer F...). The aforementioned stacked paramagnetic metal layers preferably have spin Nernst angles of the same sign. This is because, during thermoelectric conversion in the thermoelectric conversion layer 202, the non-reciprocal thermoelectric signals generated by each of the multiple paramagnetic metal layers will not cancel each other out, thereby increasing the overall non-reciprocal thermoelectric signal.

[0124] Furthermore, in the above embodiments, the thermoelectric conversion layer 202 has only one paramagnetic metal layer (paramagnetic metal layer 205) (see reference). Figure 3 and Figure 4However, the thermoelectric conversion layer 202 can also have a first paramagnetic metal layer and a second paramagnetic metal layer. In this case, the thermoelectric conversion layer 202 is composed of a first paramagnetic metal layer, a ferromagnetic metal layer 203, and a second paramagnetic metal layer stacked in this order along the Z-axis, with the ferromagnetic metal layer 203 positioned between the first and second paramagnetic metal layers. The preferred constituent materials of the first and second paramagnetic metal layers are the same as those of the paramagnetic metal layer 205, but the composition (constituent materials and film thickness, etc.) of the first and second paramagnetic metal layers is selected such that the thermoelectric conversion layer 202 has a structure with spatial inversion symmetry broken along the Z-axis.

[0125] In this case, the first paramagnetic metal layer and the second paramagnetic metal layer preferably have spin Nernst angles with opposite signs. (This can be achieved, for example, by making the first paramagnetic metal layer Pt and the second paramagnetic metal layer Ta.) Thus, during thermoelectric conversion in the thermoelectric conversion layer 202, spin currents with the same directional polarity are injected from the first and second paramagnetic metal layers into the ferromagnetic metal layer 203, thereby increasing the non-reciprocal thermoelectric signal.

[0126] Furthermore, in this case, each or one of the first and second paramagnetic metal layers can also be composed of a plurality of stacked paramagnetic metal layers as described above. In this case, for the reasons stated above, the plurality of paramagnetic metal layers constituting each or one of the first and second paramagnetic metal layers preferably have spin Nernst angles of the same sign.

[0127] Furthermore, in the above embodiments, a pair of electrodes 207a and 207b are disposed on the upper surface 205S of the paramagnetic metal layer 205 (see reference). Figure 3 and Figure 4 This allows a pair of electrodes 207a and 207b to be disposed on the lower surface (the negative side of the Z-axis) of the ferromagnetic metal layer 203 in a manner that is not in contact with the paramagnetic metal layer 205 and is spaced apart from each other along the X-axis.

[0128] Furthermore, in the above embodiments, a thermoelectric conversion layer 202 is formed by sequentially stacking a ferromagnetic metal layer 203 and a paramagnetic metal layer 205 on a substrate 201 (see reference). Figure 3 and Figure 4 Alternatively, a thermoelectric conversion layer 202 can be formed by sequentially stacking a paramagnetic metal layer 205 and a ferromagnetic metal layer 203 on the substrate 201. In this case, a pair of electrodes 207a and 207b can be disposed on the upper surface (the positive side of the Z-axis) of the ferromagnetic metal layer 203 or the lower surface (the negative side of the Z-axis) of the paramagnetic metal layer 205, spaced apart from each other along the X-axis direction.

[0129] The following are specific embodiments of the present invention to provide a more detailed description of the invention. However, the present invention is not limited to these embodiments.

[0130] [Example of thermoelectric conversion element manufacturing]

[0131] Production as described below Figure 3 The thermoelectric conversion element 200 corresponds to the component. First, a Si substrate with a thermal oxide film and a thickness of 0.5 mm is prepared as substrate 201. On this substrate, a Ni-Fe alloy layer with a thickness of 5 nm as a ferromagnetic metal layer 203 and a Pt layer with a thickness of 5 nm as a paramagnetic metal layer 205 are sequentially deposited by DC magnetron sputtering to form thermoelectric conversion layer 202. Then, the thermoelectric conversion layer 202 is patterned by photolithography and lift-off to make it rectangular with a width of 5 μm in the Y-axis direction and a length of 50 μm in the X-axis direction when viewed from above. Then, a Ti / Au layer is deposited on the thermoelectric conversion layer 202 by radio frequency magnetron sputtering, and the Ti / Au layer is patterned into a specified shape by photolithography and lift-off to form a pair of electrodes corresponding to a pair of electrodes 207a and 207b, thus fabricating the component corresponding to thermoelectric conversion element 200.

[0132] [Example 1]

[0133] Production Figure 7 A conceptual atomic battery is shown. Plutonium-238 is implanted into a sapphire substrate using an accelerator, and a Pt (5 nm) = Py (5 nm) two-layer film (thermoelectric conversion element) is fabricated by radio frequency magnetron sputtering. The film is patterned into a rectangular element with a width of 5 μm and a length of 50 μm by electron beam lithography and Ar ion etching. The resulting atomic battery is placed in a magnetic field at room temperature, and the nonlinear voltage is measured.

[0134] [Example 2]

[0135] Production Figure 7 A conceptual atomic battery is shown. Curium-244 is implanted into a sapphire substrate using an accelerator, and a Pt (5 nm) = Py (5 nm) two-layer film (thermoelectric conversion element) is fabricated by radio frequency magnetron sputtering. The film is patterned into a rectangular element with a width of 5 μm and a length of 50 μm by electron beam lithography and Ar ion etching. The resulting atomic battery is placed in a magnetic field at room temperature, and the nonlinear voltage is measured.

[0136] The thermoelectric conversion element manufactured in the embodiments can generate thermoelectric signals nonlinearly relative to the direction of a temperature gradient, thus enabling thermoelectric conversion from microscopic temperature fluctuations that are substantially free of temperature gradients on a macroscopic scale. Therefore, in the atomic batteries of Examples 1 and 2, which contain radioactive isotopes in their structural components, electrical energy can be generated from the heat of radiation randomly generated by the radioactive isotopes. Thus, unlike conventional atomic batteries, the atomic battery of this disclosure is lightweight and thin-film-based because no components for forming temperature gradients in the thermoelectric conversion element are required. Furthermore, since thermoelectric conversion can be performed from microscopic fluctuations, power generation can be achieved using extremely weak radiation, resulting in minimal aging of the atomic battery due to radiation. Therefore, it can be applied to power sources for radiation therapy, space exploration, military equipment generators, signal light generation, and nuclear energy (e.g., generating electricity from spent fuel shielding containers).

[0137] Furthermore, the present invention has been described in detail with reference to specific embodiments, but it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

[0138] [Postscript]

[0139] The atomic energy cell disclosed herein is lighter, smaller, and more efficient than existing atomic energy cells. Therefore, it can contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs).

[0140] • Goal 9: "To create the foundation for industrial and technological innovation."

Claims

1. An atomic energy battery, characterized in that, It is an atomic energy battery containing a thermoelectric conversion element, which includes: It exhibits a thermoelectric conversion unit based on the breaking of spatial inversion symmetry, which is non-reciprocal conduction, and, A pair of electrodes, spaced apart from each other, are used to extract non-reciprocal thermoelectric signals. At least one structural component constituting the atomic battery contains a radioactive isotope element.

2. The atomic energy battery according to claim 1, wherein, The thermoelectric conversion section is a thermoelectric conversion layer comprising stacked ferromagnetic metal layers and paramagnetic metal layers. The pair of electrodes are disposed at intervals in the in-plane direction of the thermoelectric conversion layer.

3. The atomic energy battery according to claim 2, wherein, The distance between the pair of electrodes is greater than 0.1 μm and less than 1000 μm.

4. The atomic energy battery according to claim 2, wherein, The paramagnetic metal layer is composed of a single layer or multiple layers stacked together, and each of the single layer or multiple layers stacked together is composed of Pt, Pd, W, AuW alloy, Ta, CuIr alloy, CuBi alloy, BiSb alloy or BiSe alloy.

5. The atomic energy battery according to claim 2, wherein, The ferromagnetic metal layer is composed of a single layer or multiple layers stacked together, and each of the single layer or multiple layers stacked together is composed of a Ni-Fe alloy, Fe, Co, Ni, Gd, CoFeB alloy or (Ga,Fe)Sb alloy.

6. The atomic energy battery according to claim 1, wherein, The radioactive isotopes include those selected from beryllium-10, carbon-14, aluminum-26, silicon-32, chlorine-36, argon-39, potassium-40, nickel-63, selenium-79, rubidium-87, zirconium-93, indium-115, cesium-137, lanthanum-138, niobium-94, technetium-98, lutetium-71, neodymium-144, samarium-146, samarium-147, gadolinium-152, platinum-190, bismuth- At least one element from the group consisting of 210, polonium-209, thorium-232, uranium-232, uranium-233, uranium-234, uranium-235, uranium-236, uranium-238, plutonium-236, plutonium-238, plutonium-239, plutonium-244, americium-241, americium-243, curium-244, curium-246, curium-247, curium-248, californium-249, and californium-251.

7. An atomic energy battery module, characterized in that, A plurality of atomic energy batteries comprising any one of claims 1 to 6, wherein the plurality of atomic energy batteries are electrically connected to each other in a manner in which non-reciprocal thermoelectric signals from each atomic energy battery are superimposed in the same polarity.

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