High Energy Conversion Efficiency Research Articles

Sulfidation of CoCuOx Supported on Nickel Foam to Form a Heterostructure and Oxygen Vacancies for a High-Performance Anion-Exchange Membrane Water Electrolyzer.

Anion-exchange membrane water electrolyzer (AEMWE) is attracting attention for hydrogen production owing to its ability to employ nonprecious metal catalysts and high energy conversion efficiency. Spinel-structured transition metal oxides exhibit excellent potential in oxygen evolution reaction (OERs). Nevertheless, the research on highly active and durable spinel-structured electrodes for the anodic OER of AEMWE is deficient. Herein, a self-supported S-CoCu oxide/nickel foam (S-CoCuOx/NF) anode was synthesized through a two-step method (electrodeposition and sulfidation). The formation of abundant oxygen vacancies and heterostructure collaboratively enhances the electron and mass transfer, resulting in an overpotential of 313 mV at 100 mA cm-2 for OER. For the lab-scale AEMWE system with the S-CoCuOx/NF anode, a current density of 1 A cm-2 was obtained at 1.87 V (cell voltage) with high durability for 110 h (1 A cm-2) at 60 °C. The results will provide insights into developing the spinel structure-derived anode for high-performance AEMWE.

High energy storage characteristics for Ba0.9Sr0.1TiO3 (BST) doped Na0.7Bi0.1NbO3 (NBN) ceramics

In recent years, lead-free energy storage ceramics have been widely used as a new type of energy storage material with great application prospects. In this study, a modified NaNbO3 (NN) based ceramic, Na0.7Bi0.1NbO3 (NBN), is used as the matrix, and Ba0.9Sr0.1TiO3 (BST) is added as a doping agent. A series of (1-x)Na0.7Bi0.1NbO3-xBa0.9Sr0.1TiO3 (xBST, x = 0.1, 0.2, 0.3, 0.4) solid solutions have been designed and prepared using the solid-phase sintering method. The breakdown field strength (Eb) of 0.3BST ceramics reached 445 kV/cm, an unexpectedly ultra-high energy storage density (W) of 4.48 J/cm3 and a recoverable energy density (Wrec) of 3.47 J/cm3. In terms of charging and discharging performance, the ceramics have a low charging and discharging time of t0.9 = 1.38 μs. In addition, 0.1BST exhibits a high energy conversion efficiency of η = 87.35 %. These results confirm that (1-x)NBN-xBST ceramics are promising energy storage materials.

Photomultiplicative and High External Quantum Efficient Energy Conversion Device for Paper Electronics

Photomultiplicative and High External Quantum Efficient Energy Conversion Device for Paper Electronics

Ballistic Thermoelectricity

The analysis of Local thermo-EMF in p-n junctions made it possible to reveal the phenomenological features of ballistic thermoelectricity. By the Curie Symmetry Principle, in polar structures of p-n junctions, the thickness of which is of the order of the electron mean free path, the contribution of ballistic effects to the formation of the total EMF is decisive. This ballistic contribution to thermo-EMF provides both high output voltages and high efficiency of DIRECT energy conversion.

High-entropy oxide, (FeCoNiMnV)xO, boost the oxygen evolution

The sluggish kinetics of the oxygen evolution reaction (OER), an essential half-reaction of water splitting, lead to high OER overpotential and low energy-conversion efficiency, hampering its industrial application. Therefore, considerable attention has been paid to the development of efficient catalysts to accelerate the OER. In this study, we synthesized the high-entropy oxides [(FeCoNiMnV)xO] and used them as efficient OER catalysts. A simple oil-phase method was used to synthesize (FeCoNiMnV)xO. The catalytic performances of the (FeCoNiMnV)xO catalysts were modified by tuning the reaction temperature. The optimized (FeCoNiMnV)xO catalyst exhibited multiple elemental interactions and abundant exposed active sites, leading to an overpotential of approximately 264 mV to reach a current density of 10 mA cm−2 in 1 M KOH and stability of 50 h at 1000 mA cm−2. Thus, a highly active OER catalyst was synthesized. This study provides an efficient approach for the synthesis of high-entropy oxides.

Thermodynamic analysis and comparison of four type CBC-ORC energy systems with regenerator using improved lunar regolith for heat storage applied to lunar base

Closed Brayton cycle (CBC)-organic Rankine cycle (ORC) system is an important option for lunar base energy system. In order to deeply explore the potential of CBC-ORC applications at lunar base, the impact of different system constructions on system performance needs to be evaluated. This paper establishes four types CBC-ORC mathematical model with different position of regenerator, and evaluates the daytime and nighttime operation characteristics of the regenerators, including thermal efficiency, thermal efficiency and power generation. The results show that the CBC regenerator can significantly improve the thermal efficiency of the system during the lunar daytime, with an increase of 15 %. However, ORC regenerator has limited improvement on system performance (only 4.28 %). In addition, the CBC regenerator can reduce the heat exchange area of solar trough collector and radiator by 60.3 % and 57.94 %, respectively. The CBC regenerator can balance the exergy destruction of each equipment, especially the evaporator. Compared with the energy system without CBC regenerator, its exergy destruction is reduced by 58 %. In summary, different demands correspond to different energy systems. Type 4 should be selected when the system is affected by limited space, high energy conversion efficiency is accomplished in limited space. If it is only to achieve high power generation, Type 3 is the best choice for the lunar base.

A Review of Polymer Electrolyte Fuel Cells Fault Diagnosis: Progress and Perspectives

AbstractPolymer electrolyte fuel cells (PEFCs) are regarded as a substitution for the combustion engine with high energy conversion efficiency and zero CO2 emissions. Stable system operation requires control within a relatively narrow range of operating conditions to achieve the optimal output, leading to faults that can easily cause accelerated degradation when operating conditions deviate from the control targets. Performance recovery of the system can be realized through early fault diagnosis; therefore, accurate and effective diagnostic characterisation is vital for long‐term serving. A review of off‐line and on‐line techniques applied to the fault diagnosis of fuel cells is presented in this work. Off‐line approaches include electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), galvanostatic charge (GSC), visualisation‐based and image‐based techniques; the on‐line methods can be divided into model‐based, data‐driven, signal‐based and hybrid methods. Since each methodology has advantages and drawbacks, its effectiveness is analysed, and limitations are highlighted.

A Synchronized Switch Harvesting Rectifier With Reusable Storage Capacitors for Piezoelectric Energy Harvesting

Synchronized ac–dc rectifiers are widely used for energy rectification in piezoelectric energy harvesting (PEH), which have to employ a bulky inductor or some dedicated flying capacitors for high energy conversion efficiency. This article proposes a synchronized switch harvesting on shared capacitors (SSHSC) rectifier achieving synchronized voltage flipping without inductors or dedicated flying capacitors for PEH. The proposed SSHSC rectifier employs only three energy-storage capacitors with a specific capacitance ratio (3:3:1). These three capacitors mainly serve as storage capacitors; they can also be reused as flying capacitors for bias-flip operations. Thanks to the capacitor-sharing technique, this SSHSC rectifier takes a small volume and fewer I/O pads compared to prior SSHC rectifiers. This design was fabricated in a 180-nm BCD process, and the measured results show 78% voltage flipping efficiency and 7.58 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> power enhancement.

Effect of deep eutectic solvent pretreatment on biohydrogen production from corncob: pretreatment temperature and duration

ABSTRACTDeep eutectic solvent pretreatment with different temperatures and durations was applied to corncob to increase hydrogen yield via photo-fermentation. The correlation of composition, enzymatic hydrolysis, and hydrogen production in pretreated corncobs, as well as energy conversion was evaluated. Deep eutectic solvent pretreatment effectively dissolved lignin, retained cellulose, and enhanced both enzymatic hydrolysis and hydrogen production. The maximum cumulative hydrogen yield obtained under a pretreatment condition of 50°C and 12 h was 677.45 mL; this was 2.72 times higher than that of untreated corncob, and the corresponding lignin removal and enzymatic reduction of sugar concentration were 79.15% and 49.83 g/L, respectively; the highest energy conversion efficiency was 12.08%. The hydrogen production delay period was shortened, and the maximum shortening time was 18.9 h. Moreover, the cellulose content in pretreated corncob was positively correlated with both reducing sugar concentration and hydrogen yield and had the strongest influence on hydrogen production.

Effects of Transition Metal Elements on Ni Migration in Solid Oxide Cell Fuel Electrodes

Solid oxide cells (SOCs), both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC), have emerged and attracted more and more attentions due to its high energy conversion efficiency and fuel flexibility. However, degradation of fuel electrodes after long-term operation remains as one of the main challenges for their commercial application. Two major types of microstructure evolution, nickel (Ni) migration and Ni coarsening in Ni - yttria-stabilized zirconia (Ni-YSZ) fuel electrodes have been widely reported, which have strong impacts on both cell performance and durability. Therefore, materials-driven research has focused on developing more robust fuel electrodes with good electrocatalytic ability. Utilization of Ni alloys has immersed as a promising concept to enhance the performance and robustness of conventional Ni/YSZ. In the present study, Ni-M (M = Fe, Cu) bimetallic fuel electrodes are applied to investigate the effects of transition metal elements on the morphological evolutions under SOFC and SOEC operations. Ni-Fe, Ni-Cu and pure Ni patterned fuel electrodes are sputtered on YSZ pellets. The electrochemical performance of these Ni-M bimetallic fuel electrodes decreases compared with pure Ni fuel electrode, while the performance degradation rate of Ni-Fe fuel electrodes is smaller than others. Besides, the spreading of Ni film on YSZ surface is observed for all samples under anodic polarization and such Ni migration is suppressed by Fe doping, whereas enhanced by Cu doping. On the other hand, the adhesion is weakened at the electrode / electrolyte interface for Ni-Cu and pure Ni fuel electrodes under cathodic polarization, while good adhesion at the interface is maintained for Ni-Fe, which correlates with the smaller performance degradation rate.

High Entropy Perovskite Electrolytes for Reversible Protonic Ceramic Electrochemical Cells

Reversible protonic ceramic electrochemical cells (R-PCECs) become cornerstones of low-temperature solid oxide electrochemical cells (SOCs) below 600 °C. Low activation energy and high energy conversion efficiency are primary significance of R-PCECs. However, electrolytes of high-performance R-PCECs still suffer from poor tolerance to complex operating conditions. To overcome their low stability and enhance proton conductivity, various cations have been doped into the Ba-based perovskite oxide electrolyte. Developing high entropy oxides by introducing multiple metal cations into A- or B- sites of the perovskite structure can be an effective solution for the structural stability. Due to the effect of the entropy-dominated stabilization in multi-doped perovskite oxides, the material can remain single phase under extreme temperatures and chemical environments. Promising high entropy stabilization concepts were adapted to electrolytes, and finally, durable proton-conducting perovskite oxide was designed. Here, we will present our recent progress on development of high entropy perovskite oxide electrolytes for R-PCECs.

Effect of Supporting Pd Nanoparticles on WOx Nanorods on Their Stability and Catalytic Activity Towards the Electrochemical Oxidation of Concentrated Formic Acid

Direct formic acid fuel cells (DFAFC) are considered one of the most promising fuel cells to penetrate the market due to their desired and unique properties. Formic acid (FA) could be easily produced from different sources (especially biomass) and is non-toxic. The FA-based fuel cell has a high open circuit potential in comparison to methanol and Ethanol1, high energy conversion efficiency, and fast kinetics. However, the major drawback that affects using DFAFCs is the catalysts' stability and reaction intermediates' poisoning effect, especially at high concentrations of FA.FA has a dual pathway mechanism: either the simple and desired pathway of direct oxidation to CO2 2 or the unfavorable indirect oxidation to poisonous CO-like species that strongly adsorb on the catalyst surface, deactivating it,3 before it is hardly oxidized in a second step to give CO2. Therefore, the catalyst should be designed to direct the reaction towards the direct pathway and facilitate the poisoning species removal. The most active catalyst for FA oxidation in acidic media is palladium4 but it is highly susceptible to CO poisoning, especially as the FA concentration increases due to the high contribution of the indirect pathway. In addition, palladium nanoparticles supported on carbon material are known to suffer from dissolution in the acidic media making the electrode unstable for long-term application.5 In this presentation, the synthesis of nonstoichiometric WOx nanorods using hydrothermal methods will be reported. The Pd nanoparticles are synthesized and loaded on the WOx nanorods using ethanol as both a solvent and a reducing agent to produce a surfactant-free Pd surface. The synthesized materials are evaluated using XRD, TEM, FT-IR, EDS, and XPS. The effect of WOx nanorods as catalyst support on Pd nanoparticles activity and stability towards the oxidation of different concentrations (1-4 M) of FA in acidic media are evaluated using cyclic voltammetry (CV) and chronopotentiometry (CP), and compared with that of carbon-supported Pd catalyst. The Pd behavior in both cases will be correlated to its chemical and physical properties and thoroughly discussed.

Experimental Demonstration of the Electric Efficiency with BZYb based Protonic Ceramic Fuel Cell

Protonic Ceramic Fuel Cell (PCFC) is expected to be the next-generation fuel cell for its higher energy conversion efficiency and lower operation temperature. BaZrO3 based oxide are potential materials as PCFC electrolyte because they have a high chemical stability under CO2 condition and high proton conductivity. We have developed PCFC using BaZr0.8Yb0.2Ox (BZYb) as the electrolyte and performed max power density 0.49 W cm–2 at 873 K. For practical use of PCFC, it is needed to conduct the higher electric efficiency and to improve the durability. Especially, improving the electric efficiency of PCFC might be difficult due to the internal current leakage by the hole creation.In this work, we have evaluated the electric efficiency using a Φ60mm anode supported PCFC (active electrode area: Φ45mm, 15.9 cm2). Thin and dense BZYb electrolyte is supported on porous Ni-BZYb cermet anode and La0.6Sr0.4CoOx cathode. The effect of fuel utilization on PCFC cell was examined and the electric efficiency of PCFC was calculated as follows:η = V / (-ΔH / nF) × Ufwhere the n and F are the mole number and the Faraday constant, respectively. ΔH is the standard combustion enthalpy of hydrogen or methane. The value of -ΔH / nF is 1.24 V or 1.04 V in the case of hydrogen supply or methane supply respectively. V is the cell voltage and Uf is the fuel utilization.Φ60mm anode supported PCFC was fabricated by tape-casting process used for the industrial production of ceramic electronic devices. NiO-BZYb anode slurry and BZYb electrolyte slurry were prepared by mixing the powder, binder, solvents and plasticizer. And then, these slurries were tape-casted respectively. The anode green sheets and the electrolyte green sheets were stacked and pressed. The anode electrolyte half-cell was obtained by firing this laminate at 1673–1773 K for 2 h. La0.6Sr0.4CoO3-δ (LSC) paste was applied to the surface of the half-cell by screen–printing, and then, fired at 1223 K for 2 h to form a cathode.The electrochemical performance of the Φ60mm anode supported PCFC was investigated at 873 K under the conditions of a humid fuel gas (i.e., 3% H2O, 48.5% N2 and 48.5% H2) and a humid air (i.e. 3% H2O and 97% air). Fuel flow rate were determined by the operational current and the fuel utilization (Uf), and air flow rate were constant at 264 cc min–1, which the air utilization (Uair) was 30% at the current of 0.3 A cm–2.Figure 1 shows the comparison of the current-voltage (I-V) and current-power (I-P) characteristics of Φ60mm and Φ20mm BZYb cell. Fuel flow rate was 100 cc min–1 at this experiment. The same electrochemical performance was observed, and the maximum power reached 7 W at 12.9 A in the case of the Φ60mm cell.Figure 2 shows the cell performance of 0.3 A cm–2 current density under the various Uf condition. The theoretical voltage line was also drawn in the figure, which was calculated by Nernst equation used the PH2 in the anode outlet gas, PO2 and PH2O in the cathode outlet gas. Cell voltage followed the same path as the theoretical voltage in the low Uf condition (Uf≦70%). On the other hand, the gap between the cell voltage and theoretical one was larger in the higher Uf condition (Uf≧80%). Anode gas diffusion overvoltage might be increased by PH2 decreasing in anode gas or the imbalanced gas flow due to decreasing the anode gas flow rate. We demonstrated that BZYb based PCFC could be operated at high Uf condition (i.e., Uf=90%) and the maximum electric efficiency was 55% (DC). This presentation is partially based on results obtained from a project, JPNP20003, commissioned by the New Energy and Industrial Technology Development Organization (NEDO). Figure 1

Stabilization of Platinum Catalyst Surface-Treated by Atomic Layer Deposition of Cobalt for Polymer Electrolyte Membrane Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) are attracting attention as next-generation energy-conversion devices because they are environmentally friendly and have high energy-conversion efficiencies. A membrane electrode assembly (MEA), composed of an anode, membrane, and cathode, is the most important part of a PEMFC where electrochemical reactions occur. A Pt/C catalyst, wherein Pt is supported on a carbon, is used as the catalyst layer for the anode and cathode. However, as Pt is a precious metal, current research is focused on reducing its loading and improving durability of PEMFCs. This study focused on improving the durability of catalysts by suppressing agglomeration, one of the degradation mechanisms of Pt catalysts. A protective layer of Co metal was deposited using the atomic layer deposition (ALD) process to improve the durability of catalysts. The ALD process is a type of chemical vapor deposition (CVD) process. This process is suitable for the PT/C catalyst as it allows for the deposition of a uniform thin film even on the porous catalyst layer. If the protective layer is thick, it may block the active site of the catalyst, resulting in decreased activity and reduced performance. However, ALD can form a thin protective layer because it can be controlled at the atomic level by adjusting the number of cycles. After fabricating a single cell using ALD Co-Pt/C as a catalyst for the cathode, The U.S. Department of Energy's electrocatalyst durability protocol was used for an accelerated degradation test (ADT). After Co-ALD was used as a cathode for 10 and 20 cycles, the active area of the Pt catalyst particles was reduced owing to the metal Co protective layer. The initial performance and electrochemical surface area (ECSA) of Co-ALD 10, 20 cycles decreased compared to the case of using Co-ALD 0 cycle. However, after ADT, the performance and ECSA reduction rate rather decreased, confirming that the co-protective layer through the plasma-enhanced atomic layer deposition (PEALD) process can improve the durability of the Pt/C catalyst. To identify the cause of the durability improvement, the cathode catalyst particles before and after ADT were compared through high resolution transmission electron microscopy (HR-TEM) analysis. As a result, in the HR-TEM images after ADT, the Pt catalyst particles were relatively uniformly distributed on the carbon support in the Co-Pt/C catalyst compared to Co-ALD 0 cycle. In addition, it was confirmed that the size of the Pt catalyst particles of Co-Pt/C was smaller than that of bare Pt/C (Co-ALD 0 cycle). It was concluded that when the Co protective layer was deposited on the Pt/C cathode, the protective layer suppressed the agglomeration of Pt catalyst particles, therefore, the increase in Pt particle size improved compared to the Co-ALD 0 cycle, and it was revealed that durability improved by suppressing catalyst degradation.

(Digital Presentation) Ethanol Electro-Oxidation Kinetics Using Activated Carbon-Supported Pt-Ag Catalysts in Alkaline Media

Due to scarcity of fossil fuels and their severe environmental consequences, the development of high efficiency energy conversion devices such as fuel cells (FCs) have gained considerable attention. The specific energy conversion efficiency of FC is highly influenced by the activity of the electrocatalysts. The Pt is widely used as an electrocatalyst due to its high activity and stability, but its high cost and depletion of resources hinder its commercialization. One of the workable strategies for the practical application of Pt is to reduce its content by alloying with some non-precious metals and simultaneously maintain its electrochemical performance. In this context, we developed a low Pt-loaded Pt-Ag/C alloy electrocatalyst via a gradual reduction process. The electrochemical performance of the as-synthesized catalyst was investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) using the three-electrode electrochemical workstation at room temperature. The electrocatalytic investigations reveal that the resultant alloy has an activity of 32.7 mA cm-2, which is significantly higher than that of Pt/C (17.6 mA cm-2) in an alkaline electrolyte and makes it a very efficient electrocatalyst for the ethanol oxidation reaction (EOR). The partial electron transfer from Ag to Pt in Pt-Ag alloy, which weakens the CO binding and poisoning effect on the surface, may be partly responsible for the enhanced catalytic activity of Pt-Ag/C. The activated carbon support also favors charge transport by transferring charge from catalytic active sites to external circuits. The stability and durability studies reveal that Pt-Ag/C performs significantly better than Pt/C, making it a viable electrocatalyst for EOR. Keywords: Direct Ethanol Fuel Cell, Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, Alloy.

Mechanisms for Charge Selectivity on Semiconducting Photocatalyst Particles

Overall-water splitting on photocatalysts provides a direct-unassisted path in the conversion of solar energy to chemical energy. Optoelectronic properties (absorbing incident light with long excited state lifetimes) and carrier selective contacts (transporting and transferring the desired electronic carrier to the targeted redox active species) are two key parameters that govern photocatalyst behavior. However, the advantageous small geometry of the highest achieving photocatalysts makes measurement of their carrier selective contacts difficult. Additionally, several mechanisms that enable high energy-conversion efficiencies and large gradients in free energy manifest only at the nanoscale at individual nanoparticle sites. SrTiO3 has been extensively studied and shown to split water with high quantum yields when decorated with HER and OER catalysts. SrTiO3 is used, in this work, as a model system to study mechanisms for charge selectivity on overall-water splitting photocatalyst particles.Here, we use three sample geometries to measure local, facet, and catalyst-dependent, electrochemical driving forces and their synergistic enhancement of carrier selectivity, (single crystal planar (b), single crystal co-facet exposed planar (a), facetted nanoparticles (c) loaded with OER and HER catalysts [{Pt/CrO3, Rh/CrO3} and CoOOH respectively]). We use ex-situ conductive atomic force microscopy to individually interrogate the electrical properties of nano-scale catalyst/semiconductor junctions decorated on facet-engineered surfaces of SrTiO3. Supporting experiments of SECM and Operando AP-XPS will be used to measure the charge carrier selectivity when an electrolyte is present and connect the ex-situ characterization observations to operando conditions. In summary, these findings demonstrate the underlying mechanisms and the degree that they play, enabling directed research of photocatalyst systems under the two dominant engineering conditions, high optoelectronic properties and charge selective contacts. Figure 1

Robust Cellulose Nanocrystal-Based Self-Assembled Composite Membranes Doped with Polyvinyl Alcohol and Graphene Oxide for Osmotic Energy Harvesting.

Osmotic energy from the salinity gradients represents a promising energy resource with stable and sustainable characteristics. Nanofluidic membranes can be considered as powerful alternatives to the traditional low-performance ion exchange membrane to achieve high-efficiency osmotic energy harvesting. However, the development of a highly efficient and easily scalable core membrane component from low-cost raw materials remains challenging. Here, a composite membrane based on the self-assembly of cellulose nanocrystals (CNCs) with polyvinyl alcohol (PVA) and graphene oxide (GO) nanoflakes as additives is developed to provide a solution. The introduction of soft PVA polymer significantly improves the mechanical strength and water stability of the composite membrane by forming a nacre-like structure. Benefiting from the abundant negative charges of CNC nanorods and GO nanoflakes and the generated network nanochannels, the composite membrane demonstrates a good cation-selective transport capacity, thus contributing to an optimal osmotic energy conversion of 6.5W m-2 under a 100-fold salinity gradient and an exemplary stability throughout 25 consecutive days of operation. This work provides an option for the development of nanofluidic membranes that can be easily produced on a large scale from well-resourced and sustainable biomass materials for high-efficiency osmotic energy conversion.

Lithium Battery SOC Estimation Based on Multi-Head Attention Mechanism and GRU Algorithm

 Pure electric vehicles have been widely used due to their non-pollution, low noise, high energy conversion efficiency and other advantages. SOC (State of Charge) is a crucial indicator for lithium batteries and pure electric vehicles. SOC cannot be directly measured. This article designs a new network structure. It is the GRU-Attention network structure. The stacked GRU algorithm in GRU-Attention network extracts the temporal characteristics of lithium battery test data, and the stacked multi-head self-attention network extracts the global information. The GRU-Attention network can avoid long-term dependency and gradient disappearance problems. The proposed network utilizes Stacked FFN as the dense layer. This article will test the network designed in the public data set at the University of Maryland. Simultaneously, this article compares the effects of different BatchSize on the performance of the algorithm. The network training process converges more effectively with a smaller BatchSize. Both too large and too small BatchSize have a negative impact on the generalization performance of the network. The extraction of the time-order character, however, may be hampered if the timestamp is too small. At the same time, the paper also compares the GRU-Attention network horizontally with the GRU and Attention networks. Eventually, the GRU-Attention network proposed in this article could better meet the estimate of the lithium battery SOC.

Decorated dislocations lead to dynamically optimized thermoelectric performance in N-type PbTe

A high thermoelectric energy conversion efficiency requires a large power factor and a low thermal conductivity over a broad temperature range. Optimizing the temperature-dependent carrier concentration and introducing structural defects are effective methods to realize these goals. In this work, we demonstrate that Ag-decorated dislocations can facilitate the dissolution of dopants into the PbTe matrix at elevated temperatures to optimize the carrier concentration in conjunction with the static doping effect of Sb. These spatially aligned and chemically decorated dislocations strongly scatter medium-to low-frequency phonons even at a rather low number density on the order of 1010 cm−2. Moreover, these dislocations show little scattering effect on electrons, maintaining a high carrier mobility. As a consequence, a maximum thermoelectric figure-of-merit, zT, of 1.5 at 750 K and an excellent average zT value of 1.1 between 300 and 800 K are obtained in Sb and dilute Ag2Te co-doped n-type PbTe. This work demonstrates that decorated dislocation networks could optimize the electrical and thermal transport properties of thermoelectrics in a wide temperature window.

Comparative analysis on high-efficiency energy conversion system with different working mediums matched with small lead-cooled fast reactor

Nuclear energy is developing toward miniaturization, high security, and efficiency. A new compact and high-efficiency energy conversion system is being developed to match the integrated and natural-circulated lead-cooled fast reactor. This energy conversion system uses a closed Brayton cycle instead of a steam Rankine cycle for its high thermoelectric conversion efficiency and simple and compact cycle arrangement. A recompression cycle is adopted to solve the heat exchanger pinch point problem while maintaining a relatively simple and compact cycle arrangement. Many mediums are used in the various Brayton cycles, including carbon dioxide (CO2), air, nitrogen, and helium, for which qualitative, but rare quantitative, assessments have been performed. In this study, systematical analysis and quantitative comparison are performed. The efficiency of the system is investigated using various typical working mediums at various split and compression ratios within the parameters of the system. According to various comparisons, the highest system conversion efficiency of CO2 in recompression Brayton cycles is 39.36% within the working temperature range of 15–560 °C under three pressure conditions (8 MPa, 13 MPa, 20 MPa), while the efficiencies of air, nitrogen, and helium are only 32.74%, 32.77%, and 32.48%, respectively. However, the efficiency of these last three working mediums will be higher under the optimal conditions of a simple Brayton cycle, which are 32.97%, 33.22%, and 33.59%, respectively. Finally, this paper proposes an energy conversion system scheme for a lead-cooled fast reactor with supercritical carbon dioxide (S–CO2) as the working fluid, a compression ratio of 2.5, a split ratio of 0.65, a maximum temperature of 560 °C, a maximum pressure of 20 MPa, and a system efficiency of 39.36%.