Relative Energy Density Research Articles

A novel micro non-imaging concentrating solar module for building façade integration

Owing to the limited installation space and relative low energy density of solar radiation, how to fully utilize the solar energy potential on the building south façade is always an important issue. In this regard, this paper proposed a faced embedded solar thermal module with mini asymmetric parabolic concentrator, which could capture solar radiation within a wide range of incidence angles with relatively high thermal conversion efficiency. The optical efficiency of the proposed solar module maintains over 0.7 with the solar projection angle increasing from 0° to 90°, which covers the annual altitude angle variation of beam solar radiation incidence on the south façade. Corresponding photo-thermal model was developed and validated with 5 days continues outdoor measurement data. The predicted values were in good consistence with the experimental data with a R2 value of 0.975. Experimental results showed a daily thermal efficiency of 0.66 during the clear sky weather. The average daily thermal efficiency of the ACPC module throughout the year was 0.47 with a constant working temperature of 60 °C. The proposed device is expected to help the building integration design towards zero carbon emission building.

The TDHF code Sky3D version 1.2

The Sky3D code has been widely used to describe nuclear ground states, collective vibrational excitations, and heavy-ion collisions. The approach is based on Skyrme forces or related energy density functionals. The static and dynamic equations are solved on a three-dimensional grid, and pairing is been implemented in the BCS approximation. This updated version of the code aims to facilitate the calculation of nuclear strength functions in the regime of linear response theory, while retaining all existing functionality and use cases. The strength functions are benchmarked against available RPA codes, and the user has the freedom of choice when selecting the nature of external excitation (from monopole to hexadecapole and more). Some utility programs are also provided that calculate the strength function from the time-dependent output of the dynamic calculations of the Sky3D code. New version program summaryProgram Title: Sky3DCPC Library link to program files:https://doi.org/10.17632/vzbrzvyrn4.2Developer's repository link:https://github.com/manybody/sky3dLicensing provisions: GPLv3Programming language: Fortran, with one post-processing utility in Python.Journal reference of previous version:: Schuetrumpf, B., Reinhard, P.G., Stevenson, P.D., Umar, A.S., and Maruhn, J.A. (2018). The TDHF code Sky3D version 1.1. Comput. Phys. Commun. 229 (2018) 211–213.Does the new version supersede the previous version?: Yes.Reasons for the new version: The capability of reproducing the nuclear strength function for a variety of newly-coded external boosts has been added.Nature of problem: Calculating nuclear multipole strength functions is a crucial probe that can help model the nuclear system and its structure properties. A variety of models exist for this task, such as QRPA (Quasiparticle Random Phase Approximation) and its variants, but such approaches are often limited due to symmetry constraints. Time-dependent Hartree Fock (TDHF) has been used to simulate nuclear vibrations and collisions between nuclei for low energies without assuming any symmetry in the system. This code extends the TDHF to calculate the multi-pole strength functions of atomic nuclei. We showcase its reliability by comparing it with the established RPA codes for the calculation of such strength functions.Solution method: We extended previous versions of the Sky3D code [1,2] to include an external boost of multipole type where the user can provide custom input that decides the nature of the multipole (monopole, quadrupole, octupole, and so on) boost. The principal aim is to calculate the multipole strength function, which is the Fourier transform of the time-dependent expectation value of the multipole operator, which has the same form as the external boost. The proper unit conversion is done so that one can extract the exact unit of the thus calculated strength function, which is comparable to the available literature in the field. The boundary conditions are chosen such that a Woods-Saxon-like function cuts off the external field, driving it to zero at the boundary.Summary of revisions: The ability to give a more general external field for excitation has been implemented, which can be of a chosen multipolarity and isospin nature. Then, as a function of time, moments for both isospins and for multipolarities up to L=5 are followed. A new analysis program is included to calculate strength functions and energy weighted sum rules. The ability to specify a mixing parameter in the pairing force is included. This allows a mixed surface-volume pairing to be selected in a way more compatable with QRPA codes for comparison. An updated Makefile is included which makes compilation on Apple silicon computers easier.

Effects of process parameters on microstructure properties of WE43 magnesium alloy by selective laser melting

Magnesium alloys have broad application in aerospace, biomedicine and automobile, et al. Selective Laser Melting (SLM) additive manufacturing of magnesium alloy can fabricate complex components with acceptable properties. However, the low evaporation heat of magnesium alloy at ambient temperature leads to vaporization instead of melting during the SLM forming process, posing significant challenges for achieving successful SLM fabrication of magnesium alloys. Hence, the objective of this paper is to analyze the impact of various process parameters on the distribution of macroscopic defects and the relative density during SLM additive manufacturing test of WE43 magnesium alloy samples. Additionally, it investigates the effect of forming parameters on the microstructure by examining molten pool morphology, grain size, and material composition. Mechanical property tests are conducted to establish correlations between relative density, microhardness, strength, and energy density in printed samples. Consequently, optimal SLM manufacturing parameters for WE43 magnesium alloy are determined as follows: laser power 200 W and scanning speed 800 mm/s. This study successfully achieves high-performance additive manufacturing of magnesium alloy materials.

Attractive (s)axions: cosmological trackers at the boundary of moduli space

We study the cosmological evolution of a FLRW universe dominated by the energy density of moduli close to asymptotic regions of moduli space. Due to the structure of the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{N}$$\\end{document} = 1 SUGRA kinetic term, a saxion and an axion residing in the same chiral multiplet are (universally) coupled even if the latter is a flat direction of the potential, resulting in non-trivial dynamics. We generalise known results in the literature to the case of multiple moduli, showing the existence of various “tracker” attractor solutions where the relative energy densities of many components (axions included) stay in a fixed ratio throughout the evolution. We conclude with some phenomenological applications, relevant for both the early and late universe.

Fully non-Gaussian Scalar-Induced Gravitational Waves

Scalar-Induced Gravitational Waves (SIGWs) represent a particular class of primordial signals which are sourced at second-order in perturbation theory whenever a scalar fluctuation of the metric is present. They form a guaranteed Stochastic Gravitational Wave Background (SGWB) that, depending on the amplification of primordial scalar fluctuations, can be detected by GW detectors. The amplitude and the frequency shape of the scalar-induced SGWB can be influenced by the statistical properties of the scalar density perturbations. In this work we study the intuitive physics behind SIGWs and we analyze the imprints of local non-Gaussianity of the primordial curvature perturbation on the GW spectrum. We consider all the relevant non-Gaussian contributions up to fifth-order in the scalar seeds without any hierarchy, and we derive the related GW energy density ΩGW(f). We perform a Fisher matrix analysis to understand to which accuracy non-Gaussianity can be constrained with the LISA detector, which will be sensitive in the milli-Hertz frequency band. We find that LISA, neglecting the impact of astrophysical foregrounds, will be able to measure the amplitude, the width and the peak of the spectrum with an accuracy up to 𝒪(10-4), while non-Gaussianity can be measured up to 𝒪(10-3). Finally, we discuss the implications of our non-Gaussianity expansion on the fraction of Primordial Black Holes.

Critical periods in the marine life history of juvenile western Alaska chum salmon in a changing climate

Recent precipitous declines in western Alaska chum salmon Oncorhynchus keta returns followed unprecedented warming in the northern Bering Sea ecosystem. To better understand the role of anomalous events on the early marine ecology of juvenile chum salmon in the northern Bering Sea, we utilized time-series observations over a 17 yr period (2003-2019) of sea surface temperature (SST) and juvenile chum salmon size (length and weight), diet, energy density, and relative abundance. Particular attention was paid to more recent (2014-2019) years in which there was unprecedented loss of sea ice in the northern Being Sea in comparison to previous warm (2003-2005) and cold (2006-2013) periods. Our findings indicate significant correlations between SST and juvenile chum salmon relative biomass (positive) and energy density (negative). We found that juvenile chum salmon were larger during warm periods than during cold periods; however, there was no significant difference in their length and weight between the warm periods. Juvenile chum salmon fed on lower quality prey during warm periods than during cold periods, with an increase in the proportion of lower quality prey during the recent warm period. Consequently, the energy density of juvenile chum salmon was also lower during warm periods than during cold periods, with the lowest values occurring during the recent warm period (2014-2019). These results identify a shift in energy allocation and/or prey quality of juvenile chum salmon with temperature and illustrate how marine ecosystems have altered the nutritional condition of juvenile chum salmon prior to winter, when energy reserves are considered critical to survival.

Facile synthesis of nanostructured sodium and MoS2 incorporated Ni-MOFs with excellent cyclic durability for symmetric supercapacitor application

Highly porous and nanostructured metal-organic frameworks (MOFs) have fascinated enormous interest as electrode active materials for electrochemical energy storage systems, whereas their practical applications are significantly hindered by their relative inferior energy density and cyclability. In this study, MoS2 with layered structure was successfully incorporated onto hierarchical Ni-MOFs via a facile hydrothermal approach. Moreover, sodium cations were introduced to improve electronic conductivity. The resulting nanocomposites (sodium ions and MoS2 incorporated Ni-MOFs) exhibited hierarchical porous structures with varying dimensions, offering increased volume for charge storage and diffusion channels for electrolyte ions. Benefiting from the unique topological architectures, the as-synthesized porous nanocomposites delivered an excellent supercapacitive performance, achieving a superlative energy of 33.33 Wh kg−1 and a power density of 3390 W kg−1. Furthermore, the as-fabricated symmetric supercapacitor device delivered a remarkable cycling durability where the acquired outstanding capacitance retention was 97.42% and coulombic efficiency was 97.82% respectively over more than 10,000 cycles in an aqueous electrolyte.

Scattering and enhancement of electromagnetic waves energy by coaxial plasma cylinders

The scattering of plane electromagnetic waves by three configurations of coaxial plasma cylinders is investigated in perpendicular incidence.‏ The results show that the electromagnetic energy enhancement and redistribution of energy are significantly affected by plasma frequency, electron neutral collision frequency, incident wave frequency, and the configuration of coaxial plasma cylinders. With increasing the collision frequency at fixed plasma frequency and incident wave frequency, the maximum relative energy density of the focal spot increases, and with a further increase in the collision frequency, the maximum relative energy density of the focal spot reaches some maximum value and begins to decrease. Furthermore, for fixed values of collision and plasma frequencies, at incident frequencies where the focal length is large, the maximum relative energy density is small. One main result obtained in this research indicates that the energy enhancement at the focal spot for TM polarization scattering is more than for TE mode. The results of this paper may be used for applications related to the redistribution and enhancement of electromagnetic energy.

Efficient pH-universal aqueous supercapacitors enabled by an azure C-decorated N-doped graphene aerogel

Current aqueous supercapacitors (SCs) possess the relative low energy density, and there is therefore widespread interest in cost-effective fabrication of capacitive materials with promoted specific capacitance and/or broadened voltage window. Here, a redox-active azure C-decorated N-doped graphene aerogel (AC − NGA) is fabricated using a simple hydrothermal self-assembly method through strong noncovalent π-π interaction. AC − NGA highlights an excellent charge storage performance (a high 591F g−1 gravimetric capacitance under a current density of 1.0 A g-1 and ultrahigh voltage window of 2.3 V) under pH-universal conditions. The capacitive contribution of charge storage is 91.7%, exceeding or comparable to those of the best pseudocapacitors known. Furthermore, a symmetric AC − NGA//AC − NGA device realizes high energy and power densities (15.2–60.2 Wh kg−1 at 650–23,000 W kg−1) and excellent cycling stability in acidic, neutral, and basic aqueous solutions. This work offers a cost-effective strategy to combine redox dye molecules with heteroatom-doped graphene aerogel for building green efficient pH-universal aqueous supercapacitors.

EuMnO3/EuMn2O5/MWCNT nanocomposites: Insights into synthesis and application as potential materials for development of hydrogen storage capacity

Although, hydrogen as a novel clean-burning fuel is the most promising option for energy production/consumption systems, the relative low volumetric energy density value has limited success in sorption abilities at ambient conditions. In response to the energy crisis, numerous studies on the rational construction of high-capacity electrode materials have been aimed to address the growing complications. Herein, a novel energetic solid composite based on nano-sized EuMnO3/EuMn2O5 incorporated with multiwalled carbon nanotube (EM/EMM/MWCNT) materials was fabricated via efficient synthesis protocols. An in-situ combustion route was proposed for interfacial architecture design of binary EM/EMM nanocomposites by manipulating the fuel concentration. The fundamental impacts of the Schiff-base ligand tris(2-(2-hydroxyacetophenylidene)ethyl)amine as both fuel and nucleation center on the crystalline phase structure and morphology features of binary EM/EMM products were investigated, for the first time. Correspondingly, the incorporation of MWCNT at varying concentrations was explored for preferable electrochemical hydrogen storage of composite texture in terms of the redox reactivity and improved electronic conductivity. When the MWCNT concentration was 3.0%, the structural advantages of the EM/EMM/MWCNT nanocomposites delivered maximum discharge capacity of 382.50 mAhg−1 after 15 cycles in 2.0 M KOH medium, which was 7.30 times higher than that yield by binary EM/EMM nanocomposites. It can be emphasized that this report suggests freestanding pathways for developing manganite-based electrode materials with highly efficient discharge capacity.

Designing Sphere-like FeSe2-Carbon Composites with Rational Construction of Interfacial Traits towards Considerable Sodium-storage Capabilities

Due to their low cost and high stability, sodium-ion batteries have been increasingly studied. However, their further development is limited by the relative energy density, resulting in the search for high-capacity anodes. FeSe2 displays high conductivity and capacity but still suffers from sluggish kinetics and serious volume expansion. Herein, through sacrificial template methods, a series of sphere-like FeSe2-carbon composites are successfully prepared, displaying uniform carbon coatings and interfacial chemical FeOC bonds. Moreover, benefiting from the unique traits of precursor and acid treatment, rich structural voids are prepared, effectively alleviating volume expansion. Utilized as anodes of sodium-ion batteries, the optimized sample displays considerable capacity, achieving 462.9 mAh g−1, with 88.75% coulombic efficiency at 1.0 A g−1. Even at 5.0 A g−1, their capacity can be kept at approximately 318.8 mAh g−1, while the stable cycling can be prolonged to 200 cycles above. Supported by the detailed kinetic analysis, it can be noted that the existing chemical bonds facilitate the fast shuttling of ions at the interface, and the enhanced surface/near-surface properties are further vitrified. Given this, the work is expected to offer valuable insights for the rational design of metal-based samples toward advanced sodium-storage materials.

Stepped partially acoustic dark matter, large scale structure, and the Hubble tension

We propose a new interacting dark sector model, Stepped Partially Acoustic Dark Matter (SPartAcous), that can simultaneously address the two most important tensions in current cosmological data, the H0 and S8 problems. As in the Partially Acoustic Dark Matter (PAcDM) scenario, this model features a subcomponent of dark matter that interacts with dark radiation at high temperatures, suppressing the growth of structure at small scales and thereby addressing the S8 problem. However, in the SPartAcous model, the dark radiation includes a component with a light mass that becomes non-relativistic close to the time of matter-radiation equality. As this light component annihilates away, the remaining dark radiation heats up and its interactions with dark matter decouple. The heating up of the dark sector results in a step-like increase in the relative energy density in dark radiation, significantly reducing the H0 tension, while the decoupling of dark matter and dark radiation ensures that the power spectrum at larger scales is identical to ΛCDM.

Construction of multi-channel basic cobalt/nickel phosphate core-shell microsphere for superior hybrid Zn-based supercapacitor performances

Although unparalleled power density and life-span are achieved by supercapacitor devices, the related lower energy density and linear decreased output voltage still limit their applications in commercial energy storage equipment. In this work, a high performance multi-channel basic cobalt/nickel phosphate core–shell microsphere (BCNP) is firstly constructed and further fabricated with rGO-Zn negative electrode to form a hybrid BCNP//rGO-Zn supercapacitor device, which delivers an outstanding energy density of 376.5 Wh kg−1 at 1.66 kW kg−1 and a stable cell output voltage at 1.5–1.8 V. The excellent energy storage performance may attribute to the following two reasons: Firstly, the in-situ ions exchanging process between large-sized BTC3− anions and small-sized inorganic anions (OH− and PO43−) can not only make BCNP inherits the high surface area of MOF parents but also produces rich “tree-vein-like” mesoporous multi-channels, which dramatically increased the capacity, ratio and life-span of BCNP core–shell microsphere. Secondly, the introduced rGO-Zn negative electrode dramatically increased the output voltage of BCNP//rGO-Zn for boosted energy density. The as-fabricated BCNP//rGO-Zn device with the loading of 4 mg active BCNP can power a 1.5 V thermometer surpass 3 h by charging about one minute, revealing its outstanding application prospect.

A Density-Dependent Target Stimulus for Inverse Bone (Re)modeling with Homogenized Finite Element Models

Inverse bone (re)modeling (IBR) can infer physiological loading conditions from the bone microstructure. IBR scales unit loads, imposed on finite element (FE) models of a bone, such that the trabecular microstructure is homogeneously loaded and the difference to a target stimulus is minimized. Micro-FE (µFE) analyses are typically used to model the microstructure, but computationally more efficient, homogenized FE (hFE) models, where the microstructure is replaced by an equivalent continuum, could be used instead. However, also the target stimulus has to be translated from the tissue to the continuum level. In this study, a new continuum-level target stimulus relating relative bone density and strain energy density is proposed. It was applied using different types of hFE models to predict the physiological loading of 21 distal radii sections, which was subsequently compared to µFE-based IBR. The hFE models were able to correctly identify the dominant load direction and showed a high correlation of the predicted forces, but mean magnitude errors ranged from − 14.7 to 26.6% even for the best models. While µFE-based IBR can still be regarded as a gold standard, hFE-based IBR enables faster predictions, the usage of more sophisticated boundary conditions, and the usage of clinical images.

Comparative trophic ecology of nearshore juvenile salmonids in Lake Ontario

The trophic ecology of juvenile salmonids in nearshore Lake Ontario is not well understood. We used stomach content and stable isotope diet and niche metrics, as well as condition metrics to understand the trophic ecology of juvenile Atlantic salmon (Salmo salar), brown trout (Salmo trutta), Chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), rainbow trout (Oncorhynchus mykiss), and lake trout (Salvelinus namaycush). Salmonids had comparable length-weight slopes and stomach mass, and allometric patterns existed between fork-length and both relative stomach content mass and energy density for all species. Interspecific differences existed with respect to diet, and the magnitude of difference generally increased with increasing body size. Small sized salmonid (fork length < 100 mm) diets mainly consisted of Diptera (% volume = 66 – 100; prey isotope %: 11.7 – 78.4), while large sized salmonids (fork length 200 – 300 mm) consumed fish (% volume = 20–100; prey isotope % = 21.5 – 42.7). Salmonids exhibited high interspecific niche overlap, with lake trout (SEAB = 22.9 ‰2) and brown trout (18.6 ‰2) having the largest isotopic niche size, and Atlantic salmon having the smallest (2.7 ‰2). Our study addressed a knowledge gap in trophic ecology between mostly stream-dwelling juvenile and open lake adult salmonid life stages, revealing differences in diet but comparable condition metrics which suggests different strategies to optimise performance in the nearshore environment.

Modeling and Comparison of Passive Component Volume of Hybrid Resonant Switched-Capacitor Converters

Hybrid and resonant switched-capacitor (SC) convertersenable efficient utilization of both active and passive components, and have the potential to achieve higher efficiency and higher power density than conventional SC and magnetic-based converters. One or more added inductors offer an additional degree of freedom in the design space. It is of great interest to understand the tradeoffsbetween capacitor and inductor size and volume allocation. In this article, we analyze the reactive energy processed by the passive components and use it to calculate the total passive component volume. It is shown that the total passive component volume of resonant SC (ReSC) converters can be expressed as a function of flying capacitor voltage ripple, and the optimized capacitor voltage ripple that minimizes the total volume is dependent on topology specific parameters and the relative energy density ratio between capacitors and inductors. Moreover, we also demonstrate through theoretical analysis and experimentation that ReSC converters use significantly less passive component volume than conventional SC and buck converters for the same amount of power converted. Next, to compare different ReSC topologies, a normalized passive volume parameter is proposed for simple and fair comparison. This can be used along with a normalized switch stress parameter (based on switch VA ratings) to create a framework to showcase the relative performance of different topologies. This framework can be used to visualize and compare the passive and active component utilization among different topologies. Additionally, the proposed reactive power analysis is extended to hybrid converters with regulation capability.

A Step in understanding the Hubble tension

As cosmological data have improved, tensions have arisen. One such tension is the difference between the locally measured Hubble constant $H_0$ and the value inferred from the cosmic microwave background (CMB). Interacting radiation has been suggested as a solution, but studies show that conventional models are precluded by high-$\ell$ CMB polarization data. It seems at least plausible that a solution may be provided by related models that distinguish between high- and low-$\ell$ multipoles. When interactions of strongly-coupled radiation are mediated by a force-carrier that becomes non-relativistic, the dark radiation undergoes a "step" in which its relative energy density increases as the mediator deposits its entropy into the lighter species. If this transition occurs while CMB-observable modes are inside the horizon, high- and low-$\ell$ peaks are impacted differently, corresponding to modes that enter the horizon before or after the step. These dynamics are naturally packaged into the simplest supersymmetric theory, the Wess-Zumino model, with the mass of the scalar mediator near the eV-scale. We investigate the cosmological signatures of such "Wess-Zumino Dark Radiation" (WZDR) and find that it provides an improved fit to the CMB alone, favoring larger values of $H_0$. If supernovae measurements from the SH0ES collaboration are also included in the analysis, the inferred value of $H_0$ is yet larger, but the preference for dark radiation and the location of the transition is left nearly unchanged. Utilizing a standardized set of measures, we compare to other models and find that WZDR is among the most successful at addressing the $H_0$ tension and the best of those with a Lagrangian formulation.

Effects of particle morphology and magnetocrystalline anisotropy on < 111 > orientation and magnetostriction of sintered Tb-Dy-Fe/DyCu compacts

Sintered Tb-Dy-Fe materials prepared by the compression molding method have higher relative density and energy density than powder-bonded composites. However, due to the low magnetocrystalline anisotropy and the cubic symmetry of the Laves structure, the orientation degree of sintered materials is relatively low and not beneficial for obtaining large magnetostriction. We prepared the sintered Tb-Dy-Fe/DyCu compacts with preferred <111 > orientation by applying magnetically oriented powder metallurgy. The dependence of orientation degree and magnetostriction of oriented Tb-Dy-Fe/DyCu sintered compacts on different particle morphology and Tb/Dy ratios were studied. The oriented Tb-Dy-Fe/DyCu sintered compacts prepared from the milled single crystal Tb-Dy-Fe powders gained a higher <111 > orientation due to the small rotational resistance when magnetic particles move in a magnetic field, achieving improved magnetostriction. Magnetocrystalline anisotropy which determines the rotational torque caused by the magnetic field is one of the important factors affecting the rotation behavior of magnetic particles in a magnetic field. We designed Tb-Dy-Fe alloys with different Tb/Dy ratios which have different magnetocrystalline anisotropy, and prepared the sintered Tb-Dy-Fe/DyCu compacts under the same process parameters. The magnetocrystalline anisotropy constant K1 of TbxDy1-xFe1.95 (x = 0.27, 0.30, 0.33, 0.50) alloys increased from 0.66 × 106 J/m3 to 3.85 × 106 J/m3 by raising the Tb/Dy ratios, and the <111 > orientation degree of sintered Tb-Dy-Fe/DyCu compacts was promoted simultaneously. The oriented Tb0.33Dy0.67Fe1.95/DyCu sintered compact achieved the highest <111 > orientation degree of 56.6%, resulting in the largest magnetostriction of 1326 ppm and the d33 peak value of 6.81 nm/A.

Realizing high energy density and efficiency simultaneously via sub-grain modification in lead-free dielectric films

Lead-free dielectric capacitors are widely used in electronic devices due to their extremely high charge-discharge rate and environmental friendly. However, the relative low energy density and poor thermal stability greatly hinders their application in high temperature. Herein, thin films of 0.85BaTiO3-0.15Bi(Mg0.5Zr0.5)O3 with columnar sub-grain structures are obtained by structural modification, which exhibit giant energy storage density 99.34 J/cm3, with energy storage efficiency 75.65% at room temperature. The improvement of energy density is realized through reducing the hysteresis loss, postponing saturation of the electric polarization and enhancing the dielectric breakdown strength simultaneously. Moreover, a good thermal stability and anti-fatigue properties are obtained in the temperature range from room temperature to 200 °C. The energy storage density can go up to 61.78 J/cm3 at 200 °C, which is much higher than those reported for other lead-free materials. Our results demonstrate that the columnar sub-grains can boost the domain dynamic and reduce leakage current, leading to an excellent energy storage performance in wide temperature range, which might also be applied to tailor the energy storage properties of other kind dielectric materials.

Ultra-stable sodium ion storage of biomass porous carbon derived from sugarcane

Development of low-cost anode for sodium-ion battery (NIB) has become the most desirable target in today’s energy demanding society. In this work, we present different treatments of sugarcane biomass to alter the lignocellulose compositions to obtain low-cost porous carbon as NIB’s anode. The optimized sugarcane biomass derived carbon presents the initial reversible capacity of 229 mAh g−1 and the reversible capacity of 189 mAh g−1 at 100 mA g−1 after 50 cycles. It is worth noting that the carbon also exhibits an extremely low voltage plateau with 74.2 % of discharge capacity originating from the voltages below 0.5 V. In addition, the sugarcane biomass derived carbon displays an ultra-stable capacity with almost no attenuation even after 2000 cycles. In consideration of the low voltage plateau, we also calculated the relative energy density (ER, combination of the capacity and voltage plateau), and a high ER of 500 Wh kg−1 in the first cycle and 416 Wh kg−1 after 50 cycles are obtained. In situ TEM analysis was conducted to investigate the structural stability of sugarcane biomass derived carbon. Small volumetric changes are observed at different charge-discharge states, indicating the structural stability of our sugarcane biomass derived carbon during sodiation-desodiation process, which is conducive to the stable cycling of Na-ions.