Rate Performance Research Articles

Kalman filtering-based decision threshold dynamic optimization in photonics-aided millimeter-wave systems

We propose a novel, to the best of our knowledge, decision threshold dynamic optimization (DTDO) method based on Kalman filtering to mitigate the nonlinear effect impacts of the time-domain jitter and saturation distortion on a bit error rate (BER) performance. This dynamic optimization method was validated in a photonics-aided W-band millimeter-wave system. Compared to nonlinear algorithms and clustering classification methods, DTDO offers lower complexity and superior dynamic tracking capabilities when optimizing the BER performance in photonics-aided systems. The four-level pulse amplitude modulation (PAM4) signal, after being transmitted over a 50-m W-band link, was equalized using a low-complexity filter, maintaining an exceptionally low BER. This approach effectively leverages the inherent low-complexity advantages of single-carrier transmission over the link.

Improving Oxygen-Redox-Active Layered Oxide Cathodes for Sodium-Ion Batteries Through Crystal Facet Modulation and Fluorinated Interfacial Engineering.

Layered oxides with active oxygen redox are attractive cathode materials for sodium-ion batteries (SIBs) due to high capacity but suffer from rapid capacity/voltage deterioration and sluggish reaction kinetics stemming from lattice oxygen release, interfacial side reactions, and structural reconstruction. Herein, a synergistic strategy of crystal-facet modulation and fluorinated interfacial engineering is proposed to achieve high capacity, superior rate capability, and long cycle stability in Na0.67Li0.24Mn0.76O2. The synthesized single-crystal Na0.67Li0.24Mn0.76O2 (NLMO{010}) featuring increased {010} active facet exposure exhibits faster anionic redox kinetics and delivers a high capacity (272.4 mAh g-1 at 10mA g-1) with superior energy density (713.9Wh kg-1) and rate performance (116.4 mAh g-1 at 1 A g-1). Moreover, by incorporating N-Fluorobenzenesulfonimide (NFBS) as electrolyte additive, the NLMO{010} cathode retains 84.6% capacity after 400 cycles at 500mA g-1 with alleviated voltage fade (0.27mV per cycle). Combined in situ analysis and theoretical calculations unveil dual functionality of NFBS, which results in thin yet durable fluorinated interfaces on the NLMO{010} cathode and hard carbon anode and scavenges highly reactive oxygen species. The results indicate the importance of fast-ion-transfer facet engineering and fluorinated electrolyte formulation to enhance oxygen redox-active cathode materials for high-energy-density SIBs.

Effect of an oral stimulation protocol on breastfeeding among preterm infants: a randomised controlled trial

ObjectivesThe objectives are to assess the effectiveness of a modified and adapted oral sensorimotor intervention (MA-OSMI) protocol for infants in India on the rate and performance of breastfeeding among preterm...

Nucleophilic Sn Seeding and Interface Engineering for Highly Stable Sodium Metal Batteries.

Sodium metal is a promising anode material for energy storage beyond lithium-ion batteries due to its abundance and low cost. However, the uncontrolled growth of dendrites and associated safety concerns have limited the practical application of sodium metal batteries (SMBs). By embedding nucleophilic tin seeds in a free-standing carbon film (FSF), here, an effective solution is developed to stabilize the sodium metal anode. The highly conductive and porous carbon matrix, intimately embedded with abundant Sn seeds (C@Sn), enables remarkably uniform sodium plating, and provides long-term stability for SMBs. Mechanistic studies confirm the formation of an Na─Sn alloy on interface which helps to lower the nucleation barrier for sodium plating. Hence, symmetric sodium cells equipped with C@Sn FSFs can sustain uninterrupted sodium plating and stripping for almost 2600h at a high areal capacity of 4mAhcm-2, achieving an average Coulombic efficiency (CE) of 99.88%. In addition, full cells prepared with commercial Na3V2(PO4)3 cathode and C@Sn-FSFs anode deliver remarkable cycling (90mAhg-1 beyond 1300 cycles at 1C) and excellent rate performance. This ingenious strategy of embedding Sn particles within a carbon matrix offers an overall compelling solution to enhance the longevity of sodium anodes.

Eco-Friendly High-Performance Symmetric All-COF/Graphene Aqueous Zinc-Ion Batteries.

Developing high-performance aqueous symmetric all-organic batteries (SAOBs) by replacing metal-based batteries or batteries with organic electrolytes is highly attractive to achieve a greener rechargeable world. However, such a new energy storage system still exhibits unsatisfactory rate capability and cycling stability due to the limitations in electrode materials screening. Here, a novel covalent organic framework (COF) containing abundant CN and CO for the electrode material is designed, which is combined with graphene and assembled into all-COF/graphene batteries for the first time. Moreover, the co-storage of Zn2+ and H+ in COF can be achieved in a mild aqueous electrolyte. Impressively, benefiting from the extended porous structure of COF, plentiful active reaction sites, more extensive electron delocalization from CO modification at molecular level, as well as enhanced fast H+ storage capacity of graphene and CO in COF, this kind of SAOBs show excellent cycle life and high rate performance (over 15000 cycles with a capacity of 80 mAh g-1 at a high current density of 5 A g-1 in pouch cell). This work will open a new window for the design of high-performance aqueous organic batteries, further moving toward a more eco-friendly electrochemical world.

Multiband Spectrum Method for Quantifying the Ionic Contribution of Volume Strategy and Filler Strategy: Enhancing the Ionic Transport Channels for Polymeric Solid-State Batteries.

As a promising solution for solid-state batteries with high energy density and safety, understanding the mechanism of fast ion conduction in polymer-ceramic composite solid-state electrolytes (CSEs) is still a challenging task. Herein, we understand the enhanced ion conduction in CSEs using a series of ionic spectra. Ionic insight is extended to ion conduction in CSEs, resolving the mechanism of fast ion migration. With the cooperation of enhanced interface and filler ion conduction, the CSE with a conductive filler exhibits ionic conductivity higher than that of CSEs with insulating fillers. Volume and filler strategies of CSE design are proposed based on volcanic maps of conductivity. An equivalent circuit is established to describe the conduction mechanism of CSEs. Specifically, Rinterface and Rfiller are in parallel to describe the cooperation of interface and filler conduction. They are in series with Rbulk, which represents a competition between the fundamental matrix and enhanced interface conduction. The proposed conduction model is verified though the energy storage performance of solid-state batteries; a fast dynamic process promises a better rate performance and cycling stability of solid-state batteries. These results provide deep insights into fast ion conduction in ceramic-polymer CSEs, which are indispensable to develop high-performance solid-state batteries.

Synergistic effect of molybdenum dioxide wrapped nitrogen doped carbon nanotubes in binder-free anodes for enhanced lithium storage properties

Molybdenum dioxide (MoO2) is regarded as a potential anode for lithium-ion batteries due to its highly theoretical specific capacity. However, its further application in lithium-ion battery is largely limited by insufficient practical discharge capacity and cyclic performance. Here, MoO2nanoparticles are in-situ grown on three-dimensional nitrogen doped carbon nanotubes (NCNTs) on nickel foam substrate homogeneously using a simple electro-deposition method. The unique structural features are favorable for lithium ions insertion and extraction and charge transfer dynamics at electrode/electrolyte interface. As a proof of concept, the as-synthesized nanocomposites have been employed as anode for lithium-ion battery, exhibiting a reversible and significantly improved discharge capacity of ∼517 mA h g-1at the current density of 150 mA g-1as well as superior cycle and rate performance. The first-principle calculations based on density functional theory and electrochemical impedance spectroscopy results demonstrate a reduced energy barrier of lithium ions diffusion, improved lithium storage behavior, reduced structure collapse, and significantly enhanced charge transfer kinetics in MoO2/NCNTs nanocomposites with respect to MoO2powder. The excellent performance makes as-prepared MoO2/NCNTs nanocomposites promising binder-free anode for high performance lithium-ion batteries. This work also provides important theoretical insights for other state-of-the-art batteries design.

From semi-starvation to the stage: a case report on indicators of low energy availability in a drug-free bodybuilder during contest preparation and peak week

Natural bodybuilding competitions involve periods of low energy availability (EA) combined with resistance training and high-protein diets to achieve extreme leanness. This study tracked a drug-free bodybuilder adopting evidence-based nutrition practices during 18 weeks of contest preparation. We measured endocrine function, resting energy expenditure, respiratory exchange ratio, body composition, resting heart rate, oral temperature, mood, and strength performance. Endocrine function was remeasured after 2 days of energy repletion. From baseline to week 18, free triiodothyronine (T3) and total testosterone (TT) fell into clinically low (2.7 pmol/L−1) and sub-clinically low (9.1 nmol/L−1) ranges. Resting energy expenditure decreased by −519 kcal (REEratio 0.78), and respiratory exchange ratio decreased from 0.95 to 0.85. Body mass reduced by −5.1 kg, with a sum of eight skinfold loss of −15.7 mm. Correlations were observed between body mass and decreases in oral temperature (r = 0.674, p = 0.002) and resting heart rate (r = 0.560, p = 0.016). Mood remained stable until the final 2 weeks and relative one-repetition maximum decreased in the squat (−5.4%), bench (−2.6%), and deadlift (−3.6%). Following 2 days of modest energy repletion, free T3 increased (18.5%), returning to sub-clinically low values (3.2 pmol/L−1), whereas TT fell (−20.9%), reaching clinically low values (7.2 nmol/L−1). These results offer insight into the dynamics of T3 and TT following a short-term period of modest energy repletion and further information on indicators of low EA during chronic energy restriction.

Ideal Bi-Based Hybrid Anode Material for Ultrafast Charging of Sodium-Ion Batteries at Extremely Low Temperatures.

Sodium-ion batteries have emerged as competitive substitutes for low-temperature applications due to severe capacity loss and safety concerns of lithium-ion batteries at - 20°C or lower. However, the key capability of ultrafast charging at ultralow temperature for SIBs is rarely reported. Herein, a hybrid of Bi nanoparticles embedded in carbon nanorods is demonstrated as an ideal material to address this issue, which is synthesized via a high temperature shock method. Such a hybrid shows an unprecedented rate performance (237.9mAhg-1 at 2Ag-1) at - 60°C, outperforming all reported SIB anode materials. Coupled with a Na3V2(PO4)3 cathode, the energy density of the full cell can reach to 181.9 Wh kg-1 at - 40°C. Based on this work, a novel strategy of high-rate activation is proposed to enhance performances of Bi-based materials in cryogenic conditions by creating new active sites for interfacial reaction under large current.

DFT-Guided Design of Dual Dopants in Anatase TiO2 for Boosted Sodium Storage.

Anatase titanium dioxide (TiO2) has drawn great attention as an anode material in sodium ion batteries (SIBs), but it suffers from the sluggish diffusion kinetics of Na+ within TiO2 and inferior electronic conductivity. Herein, under the guidance of density functional theory (DFT), we propose a nitrogen and selenium dual-doped TiO2 system as an advanced SIB anode. Both DFT and experimental investigations reveal the cooperative effect of dopants in boosting the electrochemical performance of TiO2, finding the optimal content ratio (N/Se at 1:3) for overall improved SIB performances. As expected, experimental results exhibit excellent sodium storage behavior of the N,Se-doped TiO2, including high discharge capacity (142 mAh g-1 at 2 A g-1), good rate performance (82 mAh g-1 at 20 A g-1), and ultralong cyclability (97% retention over 5000 cycles at 2 A g-1). Our study underscores the importance of dual-heteroatom doping in the rational design of advanced electrode materials.

In–Li Counter Electrodes in Solid‐State Batteries – A Comparative Approach on Kinetics, Microstructure, and Chemomechanics

AbstractA key challenge for solid‐state batteries is the fabrication of high‐capacity cathodes with high area loading and good rate performance. To reliably quantify the performance of high‐capacity cathodes, electrochemically stable, and high‐rate counter electrodes are essential. Otherwise, a three‐electrode setup is required. In–Li alloy electrodes are used for years in a kind of standard approach, since these seem to offer stable operation. In this comparative study, seven preparation methods for In–Li electrodes are examined, determining their suitability for cathode testing. The microstructure of a planar (i.e., foil) and a particle‐based (i.e., composite) anode configuration is analyzed in more detail. Their rate‐dependent electrode performance as well as electrochemical and chemomechanical reversibility in full‐cell configuration are analyzed. The combined results demonstrate the limitations of In–Li electrodes for high‐capacity testing, especially at high rates, while confirming their suitability for simple lab‐scale testing. Preparation significantly influences the electrode microstructure and kinetics, consequently impacting the performance benchmarks of cathodes. These findings underscore both the challenges involved in applying In–Li counter electrodes and the resulting limited comparability of results from different laboratories.

Engineering Stable Decomposition Products on Cathode Surfaces to Enable High Voltage All‐Solid‐State Batteries

Sulfide solid electrolytes such as Li6PS5Cl hold high promise for solid state batteries due to their high ionic conductivity; however, their oxidation potential of ~2.5 V is not compatible with high voltage Ni‐rich cathodes such as LiNixCoyMn1−x−yO2 (x≥0.8). Here, we devise an effective, conformal and thin coating on the cathode active material guided by density functional theory, which suppresses the oxidative decomposition of Li6PS5Cl as shown by experiment. The nanometric coating on nickel‐rich NMC85 enabled capacity retention of 82% after 200 cycles (2.8‐4.3 V vs Li+/Li) using Li6PS5Cl as the solid electrolyte. In comparison, cells with an uncoated CAM only displayed 56% capacity retention. The coated‐NCM85 cells also demonstrate much better rate performance and higher capacity. The enhanced performance is due to the formation of a stable amorphous cathode‐electrolyte interphase accruing from the decomposition products of the LiPO2F2 precursor (as predicted by DFT), which protect the sulfide electrolyte from oxidation. The coating fabricated in this cost‐effective process showed superior performance to state‐of‐the‐art coatings such as LiNbO3. This work highlights the importance of rationally designing stable coating materials based on their potential decomposition products and confirms the suitability of a low‐cost and conformal coating to enable sulfide electrolyte‐based all‐solid‐state batteries.

Entropic Design of Anionic Site to Improve Anionic Redox Stability in Lithium-Rich Cathode.

Cobalt-free manganese-rich layered oxide is considered one of the most promising cathode materials for next-generation lithium-ion batteries due to its high capacity and low cost. However, irreversible anionic redox (OAR) leads to serious failure problems and hinders its wide application. To solve the above problems, the entropy design strategy of anionic sites is proposed, which is more direct and relevant to the regulation of the OAR process compared to the traditional entropy design of TM sites. The entropic design improves the structural diversity and long-range disorder of the material, which effectively inhibits oxygen release and drastic structural strain, and alleviates structural degradation. After 400 cycles at 1C, the capacity and voltage decay per cycle are only 0.092 mAhg-1 and 1.36mV, respectively. The long cycle test (10C and 1000 cycles) at high current shows that the voltage and capacity decay are only 0.04 mAhg-1 and 0.66mV per cycle, respectively. Meanwhile, the rate performance at 10C reaches 175 mAhg-1. The charge compensation regulation and performance enhancement mechanism are investigated by systematic in-situ/ex-situ characterization and theoretical calculation. This research provides new ideas for the design of lithium-rich cathodes with stable OAR and high structural adaptability.

Engineering Stable Decomposition Products on Cathode Surfaces to Enable High Voltage All-Solid-State Batteries.

Sulfide solid electrolytes such as Li6PS5Cl hold high promise for solid state batteries due to their high ionic conductivity; however, their oxidation potential of ~2.5 V is not compatible with high voltage Ni-rich cathodes such as LiNixCoyMn1-x-yO2 (x≥0.8). Here, we devise an effective, conformal and thin coating on the cathode active material guided by density functional theory, which suppresses the oxidative decomposition of Li6PS5Cl as shown by experiment. The nanometric coating on nickel-rich NMC85 enabled capacity retention of 82% after 200 cycles (2.8-4.3 V vs Li+/Li) using Li6PS5Cl as the solid electrolyte. In comparison, cells with an uncoated CAM only displayed 56% capacity retention. The coated-NCM85 cells also demonstrate much better rate performance and higher capacity. The enhanced performance is due to the formation of a stable amorphous cathode-electrolyte interphase accruing from the decomposition products of the LiPO2F2 precursor (as predicted by DFT), which protect the sulfide electrolyte from oxidation. The coating fabricated in this cost-effective process showed superior performance to state-of-the-art coatings such as LiNbO3. This work highlights the importance of rationally designing stable coating materials based on their potential decomposition products and confirms the suitability of a low-cost and conformal coating to enable sulfide electrolyte-based all-solid-state batteries.

A W/Al Co-doped Na0.44MnO2 Cathode Material for Enhanced Sodium-Ion Storage.

The Na0.44MnO2 cathode has attracted enormous interest owing to its low cost, low toxicity, and stable structure, but its practical application is still hindered by the limited sodium storage sites. Element doping is widely used to improve its capacity. However, cation and anion substitution could barely reach a satisfactory compromise between the structural stability and reversible capacity. Herein, we show that the above issue could be overcome via the synergetic effect of W and Al substitution. Combining the electrochemical and in situ X-ray powder diffraction (XRD) measurements, we reveal that the substitution of W effectively facilitates the tunnel-to-layered phase transformation, while the further substitution of Al eliminates the Na+/vacancy ordering during the extraction/insertion of Na+ ions, resulting in a layered Na0.44Mn0.94W0.01Al0.05O2 (NMO-1W5Al) with negligible Na+/vacancy ordering upon cycling. In addition, NMO-1W5Al represents a wider Na+ interlayer spacing to accelerate the diffusion of Na+, which improves the rate performance. The high specific capacity, remarkable rate performance, and high cycling stability of NMO-1W5Al are promising for large-scale energy storage systems.

Physical Layer Security in RIS-NOMA-Assisted IoV Systems with Uncertain RIS Deployment

Reconfigurable intelligent surfaces (RISs), as an emerging radio technology, are widely used to expand the transmission distance and structure cascade channels to improve the performance of communication systems. However, based on the continuous development of wireless communication technology, as Internet of Vehicles (IoV) communication systems assisted with RIS and non-orthogonal multiple access (NOMA) can improve the overall transmission rate and system performance, the physical layer security (PLS) issue has gradually attracted attention and has become more and more important in the application of the system. In this paper, our aim is to investigate the potential threats for PLS, where an RIS is utilized in order to improve the security of wireless communications. In particular, we consider the non-fixed RIS location and wiretapping behavior of eavesdroppers on the data in this work, and further analyze the maximum safe-rate for above location assumptions. Numerical results reveal that RIS provides significant advantages on security performance, as well as providing a useful reference for the security design of future wireless communication systems, which verify the correctness of our analysis and the effectiveness of the proposed scheme.

Direct Epitaxial Growth of Polycrystalline MOF Membranes on Cu Foils for Uniform Li Deposition in Long‐life Anode‐free Li Metal Batteries

AbstractAnode‐free Li‐metal battery (AFLMB) is being developed as the next generation of advanced energy storage devices. However, the low plating and stripping reversibility of Li on Cu foil prevents its widespread application. A promising avenue for further improvement is to enhance the lithophilicity of Cu foils and optimise their surfaces through a metal–organic framework (MOF) functional layer. However, excessive binder usage in the current approaches obscures the active plane of the MOF, severely limiting its performance. In response to this challenge, MOF polycrystalline membrane technology has been integrated into the field of AFLMB in this work. The dense and seamless HKUST‐1 polycrystalline membrane was deposited on Cu foil (HKUST‐1 M@Cu) via an epitaxial growth strategy. In contrast to traditional MOF functional layers, this binder‐free polycrystalline membrane fully exposes lithophilic sites, effectively reducing the nucleation overpotential and optimising the deposition quality of Li. Consequently, the Li plating layer becomes denser, eliminating the effects of dendrites. When coupled with LiFePO4 cathodes, the battery based on the HKUST‐1 membrane exhibits excellent rate performance and cycling stability, achieving a high reversible capacity of approximately 160 mAh g−1 and maintaining a capacity retention of 80.9 % after 1100 cycles.

Nickel Vanadate Cathode Induced In Situ Phase Transition for Improved Zinc Storage by Low Migration Barrier and Zn2+/H+ Co-Insertion Mechanism.

Designing cathode materials that exhibit excellent rate performance and extended cycle life is crucial for the commercial viability of aqueous zinc (Zn)-ion batteries (ZIBs). This report presents a hydrothermal synthesis of stable Ni0.22V2O5·1.22H2O (NVOH) cathode material, demonstrating high-rate performance and extended cycle life. A successful in situ phase transformation yields Zn3(OH)2V2O7·nH2O (ZVO), which undergoes an irreversible phase transition and exhibits exceptional energy storage properties. The procedure maintains the lattice structure of ZVO and ensures high structural stability throughout the phase transformation. The NVOH cathode material exhibits the discharge capacities of 399mA h g-1 at a rate of 1 A g-1 after 400 cycles and 303mA h g-1 at 10 A g-1 after 2000 cycles. Density functional theory calculations indicate that the material is protected by electrostatic forces and exhibits structural stability, with a Zn-ion migration barrier of 0.32eV across the host lattice and the electrode-electrolyte interface. Due to these properties, NVOH also exhibits high energy/power densities of 395Wh kg-1/406W kg-1 at 0.5 A g-1 and 288Wh kg-1/8830W kg-1 at 10 A g-1. Ex situ characterizations indicate structural modifications and irreversible phase changes of NVOH, highlighting the potential of H+ intercalation and in situ phase transitions for high-performance aqueous ZIBs.

Dual Redox Reactions of Silver Hexacyanoferrate Prussian Blue Analogue Enable Superior Electrochemical Performance for Zinc‐ion Storage**

AbstractPrussian blue analogues (PBAs) have been employed as host materials of aqueous zinc‐ion batteries (ZIBs), however, they suffer from low capacity and poor cycling stability due to limited electron transfer and the presence of interstitial water in PBAs. Herein, a vacancy and water‐free silver hexacyanoferrate K0.95Ag3.05Fe(CN)6 (AgHCF‐3) was synthesized by adjusting the ratio of K and Ag in the framework. It offers nearly four electrons involving two sequential redox reactions, namely, Fe3+/Fe2+ and Ag+/Ag0, to deliver a large capacity of 179.6 mAh g−1 at 20 mA g−1 with Coulomb efficiency of ~100 %. The Zn//AgHCF‐3 cell delivers an estimated energy density of 200 Wh kg−1, surpassing reported PBAs‐based ZIBs. The formation of Ag0 in the cycling process merits favorable rate performance of AgHCF‐3 (156.4 mAh g−1 at 200 mA g−1 with 80.3 % capacity retention after 100 cycles). This investigation paves new pathways for high‐capacity PBA cathodes.

An Ultrafast and Ultralow‐Temperature 3D‐Printed All‐Organic Proton Pseudocapacitor

AbstractA critical challenge for pseudocapacitors applications is the rapid capacitance fading under extreme environments, which originates from sluggish diffusion kinetics of inorganic materials and tortuous ionic channels in conventional bulk electrodes. Herein, a novel 3D‐printed all‐organic proton pseudocapacitor (composed of 2,6‐diaminoanthraquinone (DQ)‐based anode and polyaniline‐based cathode) with chemical and structural stability is developed, which exhibits an extraordinary rate performance and cycle stability under ultralow temperature. The DQ molecules are anchored on reduced graphene oxide, which enhances the electronic conductivity and structural stability. Theoretical calculation and spectroscopic characterization reveal that the two‐electron transfer process involves quinone/hydroquinone transition. Exploiting the synergy of fast reaction kinetics of organic and the efficient ion diffusion paths of the 3D architecture, the 3D‐printed anode achieves an impressive areal capacitance of 10.14 F cm−2 at high mass loading (28.73 mg cm−2). The 3D‐printed all‐organic proton pseudocapacitor shows stable cycling performance at −80 °C and releases a high energy density of 0.76 mWh cm−2 at −60 °C. This work is instructive for the development of competitive ultra‐low temperature energy storage devices via integrating organic materials and 3D architectural electrode designs.