Output Energy Stability Research Articles

Design and Analysis of a Vertical Axis Ocean Current Turbine Tunnel Using SolidWorks Computational Fluid Dynamics

The development of renewable energy in the marine power generation sector presents a promising approach to producing electrical energy in a sustainable and environmentally friendly manner. Indonesia, with its vast oceanic territory, holds significant potential for harnessing marine energy. However, the relatively slow speed of ocean currents in the region, typically ranging from 0.1 m/s to 1.5 m/s, poses a challenge to the efficiency of marine power generation. To overcome this limitation, this research focuses on the design and analysis of a vertical-axis ocean current turbine tunnel aimed at increasing the speed of ocean currents, thereby enhancing the overall efficiency of energy production. The study combines a thorough literature review with experimental research methods, utilizing SolidWorks Computational Fluid Dynamics (CFD) software to simulate the tunnel's impact on ocean current velocity. The simulations reveal that the tunnel construction significantly boosts current speeds, increasing them from 1.0 m/s to 1.7 m/s, and from 1.5 m/s to 2.6 m/s. This increase in velocity directly translates to higher kinetic energy available for conversion into electrical power by the turbine. Moreover, the study shows that the tunnel construction contributes to a more uniform flow of ocean currents, as evidenced by the Reynolds numbers obtained—100.250 at a current speed of 1.0 m/s and 150.375 at 1.5 m/s. These values, being below 2000, indicate laminar flow conditions within the tunnel, which are beneficial for optimizing turbine performance by reducing turbulence and ensuring a stable energy output. The findings underscore the effectiveness of the tunnel design in improving the efficiency of vertical-axis ocean current turbines, making it a viable solution for enhancing renewable energy production in regions with low ocean current speeds.

Flexible Zn-ion Electrochromic Batteries with Multiple-color Variations.

Electrochromic batteries as emerging smart energy devices are highly sought after owing to their real-time energy monitoring through visual color conversion. However, their large-scale applicability is hindered by insufficient capacity, inadequate cycling stability, and limited color variation. Herein, a flexible Zn-ion electrochromic battery (ZIEB) was assembled with sodium vanadate (VONa+) cathode, ion-redistributing hydrogel electrolyte, and Zn anode to address these challenges. The electrolyte contains anchored -SO3 - and -NH3 +, which facilitates ionic transportation and prevents Zn dendrite formation by promoting orientated Zn2+ deposition on the Zn (002) surface. The ZIEB exhibits a continuous reversible color transition, ranging from fully charged orange to mid-charged brown and drained green. It also demonstrates a high specific capacity of 302.4 mAh ⋅ g-1 at 0.05 A ⋅ g-1 with a capacity retention of 96.3 % after 500 cycles at 3 A ⋅ g-1. Additionally, the ZIEB maintains stable energy output even under bending, rolling, knotting, and twisting. This work paves a new strategy for the design of smart energy devices in wearable electronics.

Flexible Zn‐ion Electrochromic Batteries with Multiple‐color Variations

AbstractElectrochromic batteries as emerging smart energy devices are highly sought after owing to their real‐time energy monitoring through visual color conversion. However, their large‐scale applicability is hindered by insufficient capacity, inadequate cycling stability, and limited color variation. Herein, a flexible Zn‐ion electrochromic battery (ZIEB) was assembled with sodium vanadate (VONa+) cathode, ion‐redistributing hydrogel electrolyte, and Zn anode to address these challenges. The electrolyte contains anchored −SO3− and ‐NH3+, which facilitates ionic transportation and prevents Zn dendrite formation by promoting orientated Zn2+ deposition on the Zn (002) surface. The ZIEB exhibits a continuous reversible color transition, ranging from fully charged orange to mid‐charged brown and drained green. It also demonstrates a high specific capacity of 302.4 mAh ⋅ g−1 at 0.05 A ⋅ g−1 with a capacity retention of 96.3 % after 500 cycles at 3 A ⋅ g−1. Additionally, the ZIEB maintains stable energy output even under bending, rolling, knotting, and twisting. This work paves a new strategy for the design of smart energy devices in wearable electronics.

A coal-based multifunctional membrane for solar-driven seawater desalination and power generation

Water evaporation systems driven by solar energy delivers great potential for seawater desalination and sustainable energy generation, which is of great significance to relieve the worldwide shortage of fresh-water and energy. However, the achievement of well-designed materials and configuration for water evaporation systems remains a great challenge, hindering the realization of high evaporation rates and stable energy output. Herein, conductive coal-based nanocarbon material was creatively fabricated to assemble a novel multifunctional membrane based evaporation system for simultaneous solar thermal desalination of seawater and power generation. The coal-based multifunctional membrane (CBMM) possesses a permanently asymmetric wetting structure, which can ensure high photothermal evaporation efficiency and stable energy output. The constructed device unit demonstrate a long and stable operation in seawater under one sun irradiance for 100 h, achieving a high evaporation rate of 1.81 kg m−2 h−1 and a large voltage output of 410 mV. Especially, multiple units of the devices can be easily connected in series or parallel to power small electronic devices. This work provides a cost-effective and large scale method for the fabrication of coal-based nanomaterials and the creative application in high-perforamnce water evaporation systems for seawater desalination and sustainable energy generation.

Emerging Nanomaterials toward Uranium Extraction from Seawater: Recent Advances and Perspectives.

Nuclear energy holds great potential to facilitate the global energy transition and alleviate the increasing environmental issues due to its high energy density, stable energy output, and carbon-free emission merits. Despite being limited by the insufficient terrestrial uranium reserves, uranium extraction from seawater (UES) can offset the gap. However, the low uranium concentration, the complicated uranium speciation, the competitive metal ions, and the inevitable marine interference remarkably affect the kinetics, capacity, selectivity, and sustainability of UES materials. To date, massive efforts have been made with varying degrees of success to pursue a desirable UES performance on various nanomaterials. Nevertheless, comprehensive and systematic coverage and discussion on the emerging UES materials presenting the fast-growing progress of this field is still lacking. This review thus challenges this position and emphatically focuses on this topic covering the current mainstream UES technologies with the emerging UES materials. Specifically, this review elucidates the causality between the physiochemical properties of UES materials induced by the intellectual design strategies and the UES performances and further dissects the relationships of materials-properties-activities and the corresponding mechanisms in depth. This review is envisaged to inspire innovative ideas and bring technical solutions for developing technically and economically viable UES materials.

Advanced flexible photocatalytic fuel cell using TiO2/carbon quantum dots photoanode for green electricity production

Flexible electronics have attracted great attention in recent years. However, the matching power sources of these flexible electronics now are mostly rigid, greatly hindering the way of all-flexible electronics. Here, a flexible photocatalytic fuel cell (fPFC) was designed to produce a stable energy output (highest power density of 40.1 mW·cm−2·g−1 in artificial sweat) while purify wasted water simultaneously. The fPFC is consisted of TiO2/carbon quantum dots (CQDs) photoanode and Ag cathode. The experimental results show that the combination of TiO2 and CQDs can broaden the range of light absorption of TiO2. Thus, the photocurrent density of TiO2/CQDs fPFC can reach up to 252.3 mA·cm−2·g−1, while the photocurrent density of pure TiO2 fPFC is 87.4 mA·cm−2·g−1. The photocurrent density of TiO2/CQDs fPFC is 188.7% higher than that of TiO2 fPFC. The maximum power density of TiO2/CQDs fPFC in flatting state is about 40.1 mW·cm−2·g−1. This TiO2/CQDs fPFC has better performance than fPFC in other literature. Besides, TiO2/CQDs fPFC in the bending state can also achieve a good performance. Four fPFCs can be easily constructed into a bracelet and generate electricity, and there is no significant change in opening voltage under flatting and bending states. This eco-friendly system has great potential in energy conservation and portable electronics, and can be applied in the following aspects: (i) wearable technology that utilizes organic waste for power generation; (ii) flexible configuration of traditional sewage treatment.

Multiscale carbon - Based ion channel fiber membrane for efficient osmotic energy capture

The green energy generated by salinity gradient at the river-sea junction can be captured by Reverse Electrodialysis (RED) technology. The ion migration in the energy conversion process occurs in the narrow ion channel inside the permeable membrane of the core component. In practical applications, membrane used for osmotic energy conversion needs to meet the necessary conditions such as effective nano-channels, sufficient surface charges, large-scale preparation and stable energy output. It is challenging to achieve all of these requirement at the same time and calls for an exquisite design of the permeable membrane. Herein, we demonstrate an ion channel membrane regulated by a carbon-based membrane with hierarchical channels for efficient osmotic energy conversion. Porous carbon (PC) nanosheets with high porosity and high modulus are filled into carbon nanofibers (CNFS)/graphene oxide (GO) composite membrane, increasing ion transport channels and providing additional space charge to improve ion selectivity. The power output from PC@GO/CNFs membranes modified with nano-porous carbon reaches 4.3 W·m−2. In addition, the ion-selective membrane obtained by this strategy has the advantages of simple process, adjustable area and good stability. This simple strategy is one of the feasible paths for infiltration to be collected effectively. Ion-selective membrane is the key component for osmotic energy conversion.

Conventional and advanced exergy-exergoeconomic-exergoenvironmental analyses of an organic Rankine cycle integrated with solar and biomass energy sources

Considering the huge consumption of traditional energy and the rising demand for electricity, the development of renewable energy is very necessary. In this paper, an energy system integrating biomass energy, solar and two-stage organic Rankine cycle (ORC) is proposed, which uses the stable energy output of biomass energy to compensate for the volatility of solar modules. The proposed system comprises a biomass boiler, photovoltaic thermal panels (PV/T), evaporators, condensers, working medium pumps, turbines, a preheater and an air preheater. In addition, conventional and advanced exergy, exergoeconomic and exergoenvironmental (3E) analyses are carried out. Conventional 3E analyses reveal two components that require priority improvement. They are respectively evaporator 1 with the largest exergy destruction (708.2 kW) and exergy destruction environmental impact rate (775.3 mPt/h) and evaporator 2 with the largest exergy destruction cost rate (19.15$/h). The results of advanced 3E analyses show that the largest avoidable endogenous exergy destruction is condenser 1 (136.6 kW), the largest avoidable endogenous exergy destruction cost rate is condenser 2 (3.377$/h), and the largest avoidable endogenous exergy destruction environmental impact rate is condenser 1 (196.1mPt/h). These mean that these components have great potential for improvement in reducing exergy destruction, saving cost and protecting the environment. In addition, the avoidable endogenous exergy destruction/cost/environmental impact rate of evaporator 2 are negative, so evaporator 2 is not suitable as a priority component for improvement, which is contrary to the conclusions of conventional 3E analyses. It is found that conventional 3E analyses can only point out the biggest exergy destruction point, but cannot indicate whether the components with the greatest exergy destruction have the greatest potential for improvement. However, advanced 3E analyses can show the improvement potential of each component by improving its own performance and the external conditions. Therefore, it is necessary to conduct advanced 3E analyses.

Heat transfer enhancement and pressure loss analysis of hydrogen-fueled microcombustor with slinky projection shape channel for micro-thermophotovoltaic system

Micro thermophotovoltaic (MTPV) system, as a type of micro-combustion power system, possesses several advantages, including higher energy density, sustained and stable energy output, and significantly extended service life. The energy conversion performance of the MTPV system is known to be closely correlated with the thermal performance of the microcombustor. This study proposes a unique microcombustor for the MTPV system with a slinky projection form channel. The influence of the amplitude of the slinky projection, the slinky projection fins number, and the basic oscillating channel radius on the external wall temperature, temperature uniformity, and pressure loss are investigated by adopting the detailed hydrogen/air reaction mechanism with 3-D numerical models. The results show that the increase of the slinky projection amplitude and the slinky projection fins number can improve the external wall temperature. Compared to the traditional microcombustor, the average external wall temperatures of the microcombustor with a slinky projection amplitude of 0.4 mm are 31.6 K lower at an input velocity of 5 m/s. Additionally, when the input mixture velocity is 5 m/s, the average outer wall temperature improves by 29.4 K as the number of slinky projection fins grows from 10 to 42, and the pressure drop increases by 1.4 times. Furthermore, the basic oscillating channel radius is suggested to be 1.5 mm. In summary, this research provides a valuable method for enhancing the energy production of the MTPV system.

A Stable and Compact Mid-IR at 6.45 μm Exceeding 6 mJ of Pulse Energy BaGa4Se7 Optical Parametric Oscillator

We experimentally demonstrate a stable and compact high pulse energy mid-infrared (MIR) 6.45 μm laser, which is produced by an optical parametric oscillator (OPO) based on the non-oxide BaGa4Se7 (BGSe) nonlinear crystal pumped by 1064 nm Nd:YAG laser oscillator. With optimizing the parameters of the OPO system, a record high idler energy of 6.76 mJ at 6.45 μm was obtained with 18.85 ns of pulse duration (FWHM) at the repetition rate of 10 Hz under 93.5 mJ of pump energy, corresponding to an optical-to-optical conversion efficiency up to 7.23% from 1064 nm to 6.45 μm. The experimental results were in close approximation with the theoretical calculations. To date, it is both the highest MIR pulse energy and the highest conversion efficiency at 6.45 μm for any 1 μm pumped OPOs. Further, excellent output energy stability is demonstrated, with an energy fluctuation of less than ±0.5% over 165 min. Such a laser is interesting for both scientific and medical applications, including, for instance, for trace gas analysis and tissue ablation.

A Functional Prelithiation Separator Promises Sustainable High‐Energy Lithium‐Ion Batteries

AbstractHigh‐energy lithium‐ion batteries built with silicon‐based anode materials are usually associated with short cycle lives due to mechanical failure at an anode level and more importantly, due to electrochemical failure at a cell level as a result of irreversible consumption of cathode Li during initial charge. (Electro)chemical prelithiation has shown promises to compensate initial Li loss and improve cycling performance of the battery. However, previous strategies applied directly at anode or cathode could raise concerns on safety and degraded electrode structure, and are less compatible with industrial manufacture of batteries. Here, a new concept of prelithiation by lithiation agents supported functional separator, which is highly adaptive to electrode preparation, battery manufacture and formation, and is capable of, by simply adjusting cell voltage, not only replenishing cathode Li loss but re‐uptaking anode Li to inhibit local over‐lithiation and dendrite formation, is shown. By employing the functional separator, a 3‐Ah Li‐ion pouch cell that pairs a silicon‐based anode and a high‐nickel layered oxide cathode demonstrates stable energy output of >330 Wh kg−1 and much improved cycling performance.

“Win‐Win” Scenario of High Energy Density and Long Cycling Life in a Novel Na3.9MnCr0.9Zr0.1(PO4)3 Cathode

The development of high‐energy and long‐lifespan NASICON‐type cathode materials for sodium‐ion batteries has always been a research hotspot but a daunting challenge. Although Na4MnCr(PO4)3 has emerged as one of the most promising high‐energy‐density cathode materials owing to its three‐electron reactions, it still suffers from serious structural distortion upon repetitive charge/discharge processes caused by the Jahn‐Teller active Mn3+. Herein, the selective substitution of Cr by Zr in Na4MnCr(PO4)3 was explored to enhance the structural stability, due to the pinning effect of Zr ions and the ≈2.9‐electron reactions, as‐prepared Na3.9MnCr0.9Zr0.1(PO4)3/C delivers a high capacity retention of 85.94% over 500 cycles at 5 C and an ultrahigh capacity of 156.4 mAh g−1 at 0.1 C, enabling the stable energy output as high as 555.2 Wh kg−1. Moreover, during the whole charge/discharge process, a small volume change of only 6.7% was verified by in situ X‐ray diffraction, and the reversible reactions of Cr3+/Cr4+, Mn3+/Mn4+, and Mn2+/Mn3+ redox couples were identified via ex situ X‐ray photoelectron spectroscopy analyses. Galvanostatic intermittent titration technique tests and density functional theory calculations further demonstrated the fast reaction kinetics of the Na3.9MnCr0.9Zr0.1(PO4)3/C electrode. This work offers new opportunities for designing high‐energy and high‐stability NASICON cathodes by ion doping.

Green-in-green biohybrids as transient biotriboelectric nanogenerators

Green self-powered devices based on biodegradable materials have attracted widespread attention. Here, we propose the construction of the transient biotriboelectric nanogenerator (TENG) using green-in-green bionanocompoites. The green-in-green nanocomposites, cellulose nanocrystal (CNC)/polyhydroxybutyrate (PHB), are prepared with a high-pressure molding method. The CNC promotes the degradation and enhances the dielectric constant of CNC/PHB. It further allows for the significant improvement of the triboelectric output of CNC/PHB-based TENG. The voltage output and current output of CNC/PHB-based TENG are 5.7 and 12.5 times higher than those of pristine PHB-based TENG, respectively. Also, the bio-TENG exhibits admirable signal stability in over 20000 cycles. Despite the high hardness of CNC/PHB, a soft but simple-structured arch sensor is successfully assembled using CNC/PHB-based TENG. It can attain the precise real-time monitoring of various human motions. This study may provide new insights into the design/fabrication of green functional materials, and initiate the next wave of innovations in eco-friendly self-powered devices.

Inside Back Cover: Volume 3 Issue 4

Inside back cover image: In this work, the bottlenecks of low cost polypyrrole in term of practical application, such as insufficient electrochemical performances and poor cycling stability, have been solved by an optimized pulse-potential polymerization strategy. This strategy effectively removed the concentration polarization effect during the electrodeposition process, leading to shorter molecular structure and homogeneous stress distribution of polypyrrole. In addition, the enhanced protonation level further boosted the charge transfer kinetics in polypyrrole. As a result, the optimized polypyrrole electrodes achieved outstanding specific capacitance and long cycle life simultaneously. The fabricated pouch supercapacitors of large size can exhibit a stable energy output and strong compressive endurance when suffering harsh scenarios of simulating real-world, which provides a promising commercial prospect for polypyrrole-based electrode materials. (DOI: https://doi.org/10.1002/smm2.1116)

Tough, flexible, and durable all-polyampholyte hydrogel supercapacitor

Most of the currently developed flexible energy storage devices lack sufficient flexibility to withstand various deformations, such as stretching, compression, and bending under the action of external forces. It also lacks sufficient and stable energy output. In this work, we use the flexible material hydrogel as electrode and electrolyte to design an all-hydrogel integrated flexible supercapacitor. Both the electrode and the electrolyte contain the same polyampholyte hydrogel P(NaSS-co-DMAEA-Q) matrix, making them possess superb self-adhesion due to the electrostatic interaction between the anion and cation group, and highly softness/toughness thanks to the energy-dissipative mechanism. The electrode of supercapacitor is a composite of activated carbon and hydrogel, which has excellent mechanical and electrical properties. Supercapacitors prepared from hydrogel electrodes and hydrogel electrolytes are inherently scalable/compressible, and simultaneously deliver high areal capacitance (128.9 mF cm−2 at 1 mV s−1 and 340.18 mF cm−2 at 0.1 mA cm−2) and maintain stable energy output. The combination of simple device structure, stable mechanical properties and excellent electrical properties makes flexible supercapacitors promising for applications in wearable electronics/devices and energy storage.

Multi-Beam Large Fundamental Mode Neodymium Glass Regenerative Amplifier With Uniform Performance

In this study, the designing method of multi-beam regenerative amplifiers with the repetitive rate was proposed and demonstrated. To obtain multi-beam regenerative amplifiers with uniform performance, the disparities in output energy, energy stability, and mode size were analyzed, and the detailed optimizing method was presented. With the designs, eight-beam regenerative amplifiers were developed. The output performances of eight-beam regenerative amplifiers were uniform. The output energies were in the range of 25.4–28.8 mJ, and the energy stabilities over two hours were in the range of 2.4%–5.1% (PV) and 0.3%–0.9% (RMS).

Metal-organic framework derived magnetic phase change nanocage for fast-charging solar-thermal energy conversion

Efficient capture, conversion and storage of solar energy has been a long-term pursuit facing the green and low-carbon strategic goal. Nevertheless, fast-charging solar-thermal conversion and sustainable stable energy output are the key challenges in current solar-thermal energy storage systems. Herein, we rationally designed a sustainable stable and fast-charging solar-driven energy storage system that can simultaneously supply electricity and heat by integrating phase change materials (PCMs) and metal-organic framework (MOF) derived magnetic Co-decorated hybrid graphitic carbon and N-doped carbon (Co-GC@NC) nanocage. Benefiting from the synergistic effect between magnetic Co nanoparticles and GC@NC carbon hybrid, the resultant magnetic carbon nanocage demonstrates superior full-spectrum absorption and Co-GC@NC-based composite PCMs exhibit a high solar-thermal conversion efficiency of 90.7%. More attractively, the solar-thermal energy conversion and storage efficiency of Co-GC@NC-based composite PCMs is significantly enhanced by 115.8% due to the excellent magnetic manipulation ability of nanocage when a magnetic field was applied. Meanwhile, the designed solar-thermal energy conversion and storage system achieves a maximum output voltage of 290 mV and current of 92.6 mA. This magnetic nanocage-accelerated strategy provides constructive insights into the targeted construction of sustainable and stable fast-charging solar-driven energy storage systems.

Direct-ink-writing of multistage-pore structured energy collector with ultrahigh ceramic content and toughness

Polymer-based piezoelectric composites with flexibility, lightweight and stable energy output play an indispensable role in self-powered portable electronic equipment. The addition of high-content ceramics to form three-dimensional porous structures can greatly improve the piezoelectric properties of the composites but adversely affects the flexibility and mechanical properties of the materials. In this study, multistage-pore structured polydimethylsiloxane (PDMS)/barium titanate (BT) composites with ultrahigh BT content and super toughness were manufactured through direct-ink-writing technology. The construction of multistage-pore structures with ultrahigh ceramic content greatly improved the mechanical and piezoelectric properties of the composites. The 80 wt% BT-filled composite shows a high open-circuit voltage of 45 V and short-circuit current of 2.7 μA with a stable output after 2500 voltage cycles. Furthermore, from the cyclic compression test to the strain of 30%, the ultimate stress only decreases by 12% after 2000 cycles, among which 95% occurred in the early stages (the first 100 cycles), which demonstrating stable and repeatable elasticity of ultrahigh BT-filled composite. This study provides insights for preparing high-ceramic-content piezoelectric composites through 3D printing technology for energy collection in wearable devices.

A solvent-exchange strategy to develop stiff and tough hydrogel electrolytes for flexible and stable supercapacitor

Toughness of flexible energy storage devices and a stable energy output during dynamic deformation are two challenges to be solved in their practically application. Herein, we reported a stiff and tough poly(vinyl alcohol) (PVA) hydrogel electrolyte for flexible supercapacitor with toughness and stable energy output. A one-step solvent-exchange strategy was developed to replace the good solvent dimethyl sulfoxide (DMSO) to a poorer one water and simultaneously introduce kosmotropic ions into the PVA pre-hydrogels. This triggered the PVA chains to self-assemble and forming a homogeneous network crosslinked by the PVA crystalline domains and hydrophobic interactions. Benefiting from the excellent energy-dissipating ability of the homogeneous network, the PVA hydrogel electrolytes exhibited remarkable stiffness and toughness with tensile strength 16.54 MPa, elongation at break 1203%, and toughness 111.21 MJ m−3, which surpassed the most reported hydrogels. By utilizing polyaniline as electrodes, a flexible supercapacitor was assembled with superior areal specific capacitance of 156.50 mF cm−2 at 1.0 mA cm−2. The supercapacitor delivered high resistance to mechanical stimuli such as bending and pressure. Moreover, it could well maintain stable energy output even being dynamically deformed. The developed supercapacitor showed great potential in the wearable applications.

Regulating Thermogalvanic Effect and Mechanical Robustness via Redox Ions for Flexible Quasi-Solid-State Thermocells

HighlightsA redox couple is employed to fulfill the dual-function of both heat-to-electricity conversion and ionic crosslinking.High thermoelectrochemical performance can be achieved at optimized redox concentration, and dual-crosslinked network ensures remarkable mechanical flexibility and robustness.The hydrogel-based quasi-solid-state thermocell can provide stable energy output under harsh mechanical stress and deformations.