Betavoltaic Battery Research Articles

Performance study of GaN-based betavoltaic nuclear batteries with 3D interfaces

This study presents a design of a 3D interface simulation model featuring an inverted pyramid structure. Our objective is to forecast the performance of GaN-based betavoltaic nuclear batteries with the PN junction 3D interface structures comparing a practical machining process. Initially, we computed the electron-hole pairs (EHPs) generation rate in GaN materials irradiated by both 63Ni and 147Pm sources using Geant4. Furthermore, we employed COMSOL Multiphysics, a finite element analysis software, to simulate the EHPs transport phenomena within the battery and investigate the influence of structural parameters on the output performance. Despite maintaining thicknesses of the P- and N-regions and consistent doping concentrations (Hp-GaN, Hn-GaN, Na, and Nd) as constants, the simulation results revealed notable disparities in the short-circuit current density (Jsc), open-circuit voltage (Voc), and maximum output power density (Pmax) among batteries irradiated with various radioactive sources. Subsequently, we investigated the output performance of the nuclear battery by altering parameters such as the number of inverted pyramid structures, junction depth, and type of radioactive source. Our investigation revealed that selecting 63Ni as the radioactive source, with Na at 1017 cm−3, Nd at 1014 cm−3, a junction depth of 0.1 μm, and inverted pyramid structures of 25, resulted in the following battery performance parameters: a short-circuit current density (Jsc) of 0.648 μA/cm2, an open-circuit voltage (Voc) of 2.3481 V, and a maximum output power density (Pmax) of 1.2949 μW/cm2. Substituting the radioactive source with 147Pm, the average short-circuit current density, Jsc, increased to 56.865 μA/cm2, and the maximum output power density, Pmax, increased to 94.975 μW/cm2, It's a significant enhancement in output performance.

Improving the efficiency and stability of betavoltaic batteries based on understanding efficiency fluctuations and gaps with theoretical limits

Wide-bandgap semiconductors are regarded as preferred materials for preparing semiconductor conversion devices in betavoltaic batteries due to their high theoretical conversion efficiency (ηc). However, there are a few comprehensive analytical studies on why the experimental values of ηc are generally much lower than the theoretical limit of ηc (ηc-limit) and how to improve ηc and its stability. In this work, combined with the energy deposition distributions of Ti3H2, 63Ni, and 147Pm2O3 radioactive sources in SiC obtained from Monte Carlo simulations, a multi-physical mechanism, multi-parameter coupling numerical model was established. This model can comprehensively analyze the output characteristics of betavoltaic batteries under the influence of actual device structural and material parameter changes. Our results show that changes in structural and material parameters cause significant variations in the collection efficiency (Q) of the radiation-generated electron–hole pair (RG-EHP). Considering structural parameters are easy to control, instabilities in actual SiC material parameters, which include electron diffusion length (Ln), hole diffusion length (Lp), and surface recombination velocity (S), are the main reason that ηc fluctuates significantly and is generally far lower than ηc-limit. Due to differences in the distribution of RG-EHP produced by different radioactive sources in SiC, the dominant parameters causing ηc fluctuations differ. By analyzing differences in recombination loss mechanisms under different radioactive sources, the device structures were designed in a targeted manner to make ηc closer to ηc-limit. Meanwhile, when the SiC material quality fluctuates, the stability of ηc increases by 58.5%, 35.3%, and 48.2% under Ti3H2, 63Ni, and 147Pm2O3, respectively.

Investigation and Analysis of Beta Radioisotopes for Optimal Use in Betavoltaic Batteries

This research aims to investigate and analyze the optimal beta radioisotopes for use in betavoltaic batteries, focusing on enhancing a betavoltaic battery’s performance and efficiency. We conducted a comprehensive analysis of 1252 radioisotopes, among which are 955 beta emitters and 502 beta-minus decay modes. We identified 27 pure beta emitters and further narrowed these down to select the most suitable candidates for betavoltaic applications. We utilized the ICRP 107 report and DECDATA auxiliary software to evaluate some characteristics and features of beta emitters. Our evaluation led to the selection of two groups of radioisotopes—3H and 63Ni from pure beta emitters, and 147Pm, 151Sm, 171Tm, and 155Eu from impure beta emitters—based on their power, minimum volume factor, and cell and source dimensions. The selected radioisotopes demonstrate the potential to significantly improve betavoltaic battery design, offering a balance between energy output and realistic dimensions for practical applications. The findings provide a framework for selecting and utilizing suitable beta emitter radioisotopes, which is crucial for advancing betavoltaic battery technology. Our results contribute to a deeper understanding of the characteristics required for optimal radioisotope selection, paving the way for more efficient and compact betavoltaic batteries.

Theoretical simulation of time-related electrical performance of 63NiO/ZnO integrated betavoltaic battery

The temporal electrical performance of a 63NiO/ZnO integrated betavoltaic battery is examined. Utilizing first-principles calculations combined with Monte Carlo simulations, we study the energy band structure and density of states of 63NiO, particularly when 63Ni undergoes a 12.5% decay. Our findings reveal that, when the 63NiO layer is 4 μm thick, the decay's impact is akin to substitution doping. Leveraging this insight, we employed Silvaco ATLAS software to simulate the time-dependent short-circuit current, open-circuit voltage, maximum output power, and energy conversion efficiency of the 63NiO/ZnO integrated betavoltaic battery. These results were compared with those of a NiO/ZnO separate betavoltaic battery. At 6.93 years, the maximum output power of the integrated and separate devices was found to be 10.19 and 9.77 nW/cm2, respectively, corresponding to 8.67% and 88.79% of their initial values. Notably, prior to this point, the integrated device exhibited significantly superior performance; at 4.58 years, it demonstrated 2.28 times higher maximum output power compared to the separate device, followed by only a slight difference in performance thereafter.

Heterojunction betavoltaic Si14C-Si energy converter

A potential opportunity to improve the integrated betavoltaic batteries and low-power cells performance is the radionuclide-activation method, which is an integrated combination of an injection source and an energy converter in the one material. Energy converters that contain an activated SiC thin film as the Si14C-Si barrier heterojunctions energy converter in betavoltaic cell are considered. The Si14C-Si heterojunction is positioned as by 14C beta source doped direct energy converting material two-in-one, for the device structure with an emitter of Si14C with optimized thickness is 0.4μm and the doping concentrations of N-SiC/p-Si are 15.7÷15.9×1017/16.2×1017÷∼1019cm−3. To ensure efficient operation of a betavoltaic element, the mathematical model determines: the short circuit current density is up to 900 nA cm−2, the open circuit voltage is up to 1.21 V, the fill factor is 0.9, the maximum output power density is up to 300 nW cm−2, the conversion efficiency is up to 16% and up to 0.5 V voltage per load in the experiment. The calculation and experimental verification results indicate that the Si14C-Si structure improved output performance of the nuclear cell by reducing the radioactive source self-absorption energy losses and due to better energy deposition distributions of inner injector. The results are valuable for optimizing the integrated betavoltaic elements production.

Structural design and optimization of 3D interface structures based on betavoltaic nuclear batteries

Structural design and optimization of 3D interface structures based on betavoltaic nuclear batteries

Optimizing Nickel Electroplating in Low-Ni Environments for Efficient Source Production in Small Plating Baths

Electroplating nickel-63, a radioactive isotope used in betavoltaic batteries and random number generators, requires precise control due to its limited availability and the generation of radioactive waste. To minimize waste and ensure effective plating, small plating baths are employed, optimizing the process within constrained conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized to determine the optimal plating conditions and limiting conditions for nickel electroplating in a small plating bath. This study focuses on the use of low-concentration nickel solutions and small plating equipment, in contrast to the common industrial practice of using high concentrations of nickel. Here, it is important to optimize the plating parameters, especially the nickel concentration, current density, and bath temperature. An average thickness of 1.8 μm was found when plating with a nickel concentration of 0.06 M, a current density of 5 mA/cm2, and a solution temperature of 40 °C, while ideal conditions were found to achieve the theoretical maximum energy and 90% release rate when plating with nickel-63 instead of Ni.

A [formula omitted]-radioisotope battery based on betavoltaic and beta-photovoltaic dual effects

Betavoltaic batteries with strontium sources are expected to achieve higher output power because of their high energy density and low self-absorption rate with the development of MEMS. However, the high energy of beta particles emitted from 90Sr/90Y can prone to radiation damage of the semiconductor. In order to exploit the high energy of beta particles emitted from 90Sr/90Y and to avoid radiation damage to the semiconductor, this paper presents a 90Sr/90Y-radioisotope battery based on betavoltaic (BV) and beta-photovoltaic (BPV) dual effects. In the work, the energy deposition of beta particles in LYSO:Ce and GaAs was simulated by Monte Carlo code, and thickness of the scintillator was determined. And the doping concentrations and junction depth of semiconductor were optimized based on the theoretical calculations to obtain the best output performance of device. When the thickness of LYSO:Ce is 0.158 cm, the output power density Pm of the optimized dual-effect battery is 0.61 μW/cm2. And the conversion efficiency of the device is 0.92%. At this time, the doping concentrations are Na=1.58×1017cm−3 and Nd=3.16×1018cm−3, and the junction depth xj=0.05μm. All calculated parameter values are considered as theoretical limit values. In addition, the contribution of BV effect and BPV effect to the output performance of the dual-effect radioisotope battery was investigated. Different scintillator thicknesses lead to different percentages of the two mechanics. In addition, the BV effect and BPV effect output proportion is also affected by the average energy of the radiation source. In the case that the average electron energy on the semiconductor surface is 0.27 MeV, the higher the radioactive source energy, the thicker the scintillator is required, resulting in more BPV effect and less BV effect.

First principles study on the time-related properties of 4H-32SiC as an energy converting material of betavoltaic batteries

The radioactive 4H-32SiC is applied as an energy converting material to fabricate high performance betavoltaic batteries. The time-related component change is considered, and the structural, stability and electrical property changes are calculated by density functional theory. As time goes by, the number of 32Si atoms decrease exponentially while the concentration of 32S increases gradually. The Si63PC64 configurations have smaller lattice constants, while the lattices of Si62PSC64 configurations are larger. All Si63PC64 and Si62PSC64 configurations have very small bandgaps indicating the metallic behavior. This suggests that the betavoltaic battery with 4H-32SiC is likely to transform into a Schottky diode over time.

Study on Process Parameters of Magnetron Sputtering Titanium Coating in Deep Porous Structures.

In order to improve the energy conversion efficiency and power density of the tritium-powered betavoltaic battery, titanium was deposited on the inner surface of the deep porous three-dimensional structure semiconductor as a tritium absorption material. Therefore, magnetron sputtering technology was used to explore the parameters of titanium coating on the inner surface of a deep porous semiconductor. First, the effects of argon pressure and sputtering power on the properties of titanium films were studied. The properties of the titanium films were characterized by a scanning electron microscope and an atomic force microscope. The optimized sputtering parameters were obtained as follows: argon pressure of 0.5 Pa and sputtering power of 80 W. Based on this parameter, the background vacuum and coating angle were changed, and the titanium film was coated in the deep porous structure. Energy dispersive spectrometry line scan and surface scan were used to analyze the coating results, which showed that these two parameters directly affected the content of titanium in the channel, and the area of titanium in the channel structure accounted for more than 50% under each test condition.

Development of a pulsed laser deposition system suitable for radioactive thin films growth

Radioactive thin films have a direct application in the development of beta-voltaic batteries. The main advantage of that kind of nuclear battery is its durability, which can range from a hundred years, depending on the half-life of the radioisotope used. In this context, Pulsed Laser Deposition (PLD) is an important tool. A relevant aspect of a system using this technique is that the main equipment is outside the chamber where the material is processed. Consequently, this feature allows the growth of radioactive thin films, as it enables the development of an arrangement where the contaminated area is controlled. In this way, the present work proposed the development of a PLD system for the growth of radioactive thin films. The PLD system was then implemented and radioactive copper targets were processed for 60 min and 120 min, resulting in radioactive thin films with an average thickness of (167.8 ± 3.7) nm and (313.5 ± 9.2) nm, respectively. Then, a study was performed about the radioactive contamination spread in the PLD system in order to prove if the filtering implemented was effective in retaining the contamination inside the vacuum chamber. Thus, it is demonstrated for the first time the feasibility of using the PLD technique in the growth of radioactive thin films, making its use possible in future studies on the development of beta-voltaic nuclear batteries.

Maximizing output power in P-N junction betavoltaic batteries via Monte Carlo and Physics-Based Compact Model Co-Simulation*

Maximizing output power in P-N junction betavoltaic batteries via Monte Carlo and Physics-Based Compact Model Co-Simulation*

Enhancing betavoltaic nuclear battery performance with 3D P+PNN+ multi-groove structure via carrier evolution

Enhancing betavoltaic nuclear battery performance with 3D P+PNN+ multi-groove structure via carrier evolution

14C diamond as energy converting material in betavoltaic battery: A first principles study

The application of radioactive semiconductors is a potential way to improve the performance of betavoltaic battery. The stability and band structure of decayed 14C diamond are investigated by density functional theory. After the decay, the 14C atoms are substituted by nitrogen atoms, and it can be seen that the corresponding C63N1 and C62N2 structures have larger lattice constants and become more unstable. The C63N1 structure is a metallic system instead of an indirect bandgap semiconductor. Different C62N2 configurations have either metallic or indirect bandgap semiconductor properties, and the bandgaps are significantly lower than those of pure diamond. The 14C diamond–12C diamond betavoltaic battery switches between a pn-junction and p-type Schottky diode with higher short-circuit current.

Limit Efficiency of a Silicon Betavoltaic Battery with Tritium Source.

An idealized design of a silicon betavoltaic battery with a tritium source is considered, in which a thin layer of tritiated silicon is sandwiched between two intrinsic silicon slabs of equal width, and the excess charge carriers are collected by thin interdigitated n+ and p+ electrodes. The opposite sides of the device are covered with a reflecting coating to trap the photons produced in radiative recombination events. Due to photon recycling, radiative recombination is almost ineffective, so the Auger mechanism dominates. An analytical expression for the current-voltage curve is obtained, from which the main characteristics of the cell, namely, the open-circuit voltage, the fill factor, and the betaconversion efficiency, are found. The analytical results are shown to agree with the numerical ones with better than 0.1% accuracy. The optimal half-thickness of this device is found to be around 1.5 μm. The maximal efficiency increases logarithmically with the surface activity of the beta-source and has the representative value of 12.07% at 0.1 mCi/cm2 and 14.13% at 10 mCi/cm2.

Low-Pressure Deuterium Storage on Palladium-Coated Titanium Nanofilms: A Versatile Model System for Tritium-Based Betavoltaic Battery Applications.

Deuterium (D2(g)) storage of Pd-coated Ti ultra-thin films at relatively low pressures is fine-tuned by systematically controlling the thicknesses of the catalytic Pd overlayer, underlying Ti ultra-thin film domain, D2(g) pressure (PD2), duration of D2(g) exposure, and the thin film temperature. Structural properties of the Ti/Pd nanofilms are investigated via XRD, XPS, AFM, SEM, and TPD to explore new structure-functionality relationships. Ti/Pd thin film systems are deuterated to obtain a D/Ti ratio of up to 1.53 forming crystallographically ordered titanium deuteride (TiDx) phases with strong Tix+-Dy- electronic interactions and high thermal stability, where >90% of the stored D resides in the Ti component, thermally desorbing at >460 °C in the form of D2(g). Electronic interaction between Pd and D is weak, yielding metallic (Pd0) states where D storage occurs mostly on the Pd film surface (i.e., without forming ordered bulk PdDx phases) leading to the thermal desorption of primarily DOH(g) and D2O(g) at <265 °C. D-storage typically increases with increasing Ti film thickness, PD2, T, and t, whereas D-storage is found to be sensitive to the thickness and the surface roughness of the catalytic Pd overlayer. Optimum Pd film thickness is determined to be 10 nm providing sufficient surface coverage for adequate wetting of the underlying Ti film while offering an appropriate number of surface defects (roughness) for D immobilization and a relatively short transport pathlength for efficient D diffusion from Pd to Ti. The currently used D-storage optimization strategy is also extended to a realistic tritium-based betavoltaic battery (BVB) device producing promising β-particle emission yields of 164 mCi/cm2, an open circuit potential (VOC) of 2.04 V, and a short circuit current (ISC) of 7.2 nA.

Exploratory study of betavoltaic nuclear battery using AlN P[sbnd]N junction

In most of the betavoltaic nuclear batteries, wide band semiconductors such as GaN and SiC have been used as an energy converter. But, the growth of these semiconductors are relatively expensive. In the present work, a new study was conducted on betavoltaic nuclear batteries. In this study, AlN betavoltaic nuclear battery driven by an 90Sr + 90Y radioisotope source was investigated. AlN is wide band semiconductor and economically viable. Then, by Monte Carlo simulation the effects of factors such as type of electrode, dimensions, thickness, and geometric model of PN junction on the battery efficiency were investigated. Finally, it was found that the cubical model has the highest amount of short circuit current, open circuit voltage, and battery efficiency. The value of short circuit current, open circuit voltage, and battery efficiency in this model are 406.05 nA, 5.43 V, and 5.16 %, respectively. In order to compare the efficiency of AlN betavoltaic nuclear battery with the efficiency of GaN and SiC betavoltaic nuclear batteries, first the optimal dimensions were investigated for each of GaN and SiC betavoltaic nuclear batteries and then based on the optimal dimensions obtained for GaN and SiC, the cubical model was investigated for them. The results of the simulations show that, the efficiency of AlN betavoltaic nuclear battery is 24 % more than GaN betavoltaic nuclear battery efficiency and 975 % more than SiC betavoltaic nuclear battery efficiency. Also, the efficiency of the AlN betavoltaic nuclear battery (simulated in this work) is about 130 % more than the efficiency of the GaN betavoltaic nuclear battery calculated by others.

Prediction of Betavoltaic Battery Parameters

The approaches for predicting output parameters of betavoltaic batteries are reviewed. The need to develop a strategy for predicting these parameters with sufficient accuracy for the optimization of betavoltaic cell design without using the simple trial and error approach is discussed. The strengths and weaknesses of previously proposed approaches for the prediction are considered. Possible reasons for the difference between the calculated and measured parameters are analyzed. The depth dependencies of beta particles deposited energy for Si, SiC, GaN, and Ga2O3 and 20% purity 63Ni and titanium tritide as radioisotope sources are simulated using the Monte Carlo algorithm taking into account the full beta energy spectrum, the isotropic angular distribution of emitted electrons and the self-absorption inside the radioisotope source for homogeneously distributed emitting points. The maximum short circuit current densities for the same semiconductors and radioisotope sources are calculated. The methodology allowing the prediction of betavoltaic cell output parameters with accuracy no worse than 30% is described. The results of experimental and theoretical investigations of the temperature dependence of betavoltaic cell output parameters are briefly discussed. The radiation damage by electrons with the subthreshold energy and the need to develop models for its prediction is considered.

Theoretical prediction of time-related performance of GaN-based p–n junction betavoltaic battery

Betavoltaic batteries can meet long-term energy supply needs. However, due to the decay of the radioactive source, the output performance of battery will change over time, and the laws of this change require elucidation to aid the battery engineer. In this study, the influences of time on the apparent power density and β-energy spectrum of the 63 Ni source were clarified. Moreover, the structural parameters, including the p-region, n-region doping concentrations, and junction depth of GaN-based (hexagonal) p–n junction, were optimized, which are 2 × 1017 cm–3, 1014 cm–3, and 0.1 μm, respectively. In particular, the time-related performance trends were analyzed, and a formula for the maximum output power density deterioration was obtained, which can be used to evaluate the performance of 63 Ni GaN-based p–n junction betavoltaic battery within 200 years. The simulation results showed that the maximum output power density of battery after 50 years is 0.243 μW cm−2, which is only 60% of the initial value. In addition, the other output performances, namely, the short-circuit current density, open-circuit voltage, fill factor, and conversion efficiency are 0.096 μA cm−2, 2.67 V, 94.3%, and 20.5%, respectively.

Betavoltaic Nuclear Battery: A Review of Recent Progress and Challenges as an Alternative Energy Source

Nuclear energy is considered a suitable and eco-friendly alternative for combating the rising greenhouse gases in the atmosphere from excessive fossil fuel consumption. Betavoltaic battery is a form of nuclear technology that utilizes the decay energy of β-emitting radioisotopes to produce electrical power. Owing to its long shelf life, high specific energy density, and ability to work under extreme conditions, it has been a subject of considerable research attention in the past few years. Despite significant research on betavoltaic battery, several impediments to realizing high energy conversion efficiency and maximum power density have yet to be overcome. This Review Article comprehensively discusses the challenges and recent research progress of betavoltaic battery development. First, promising strategies for improving betavoltaic battery performance, theoretical principles, and equations for quantifying betavoltaic battery efficiency are discussed. Then a thorough overview of several β-radiation absorbing materials, such as traditional semiconductors, metal oxides, and organic/inorganic materials, is explored. Finally, the outlook for betavoltaic battery is discussed before concluding the review.