Ultrafast Rate Research Articles

Excellent energy density and power density achieved in NaNbO3-based relaxor ferroelectric ceramics

(1-x)NaNbO3-xBi(Ni0.5Hf0.5)O3 [(1-x)NN-xBNH, x = 0.10, 0.15, 0.20 and 0.25] lead-free ferroelectric ceramics were fabricated via a standard solid-phase reaction method, in order to obtain superior energy storage properties. BNH is introduced into the NN lattice to limit grain growth and improve the breakdown field strength as a second component. As the results indicate, a high Wrec of 6.45 J/cm3 and a breakdown field strength (Eb) of 380 kV/cm were achieved for the 0.80NN-0.20BNH ceramic, which was dependent on the nonequivalent replacement at the B site. In addition, the ceramics maintain significant stability over a frequency range of 10 Hz to 1000 Hz and temperature intervals from 30 up to 120 °C. Exceptional charge/discharge properties of high power density (PD = 215 MW/cm3) and current density (CD = 1346 A/cm2) along with an ultra-fast discharge rate (54 ns) were acquired. These results demonstrate that the 0.80NN-0.20BNH ceramic is an energy storage material with high potential.

Modulating polarization and carrier migration characteristics via constructing sandwich-structured heterojunction interfaces for achieving excellent high-temperature energy storage properties in polymer nanocomposites

Dielectric polymer nanocomposites are ideal choices for electrostatic energy storage due to their high power density and reliability, but they cannot operate efficiently at high temperature. To solve this issue, herein, we designed and developed sandwich-structured montmorillonite (MMT)/polyetherimide (PEI)-(Pb,La)(Zr,Sn,Ti)O3 (PLZST) antiferroelectrics (AFEs)@dopamine (DA)-MMT/PEI nanocomposites. On one hand, compared to current wide-band gap fillers, i.e., TiO2, Al2O3, ZrO2, and MgO, two-dimensional MMT nanosheets possess unique electrically insulating performances along the thickness direction, and thus can effectively stop charges injecting and migrating, causing low conduction loss, and large breakdown strength (Eb). On the other hand, PLZST AFEs with orthorhombic structure can exhibit high maximum electric displacement (Dmax) and small remnant electric displacement (Dr) at high temperature, which is beneficial for achieving large Dmax-Dr in the nanocomposites. In addition, large dielectric constant differences between MMT/PEI and PLZST@DA/PEI layers can inhibit electrical tree growth, resulting in further raised Eb. Finite element simulations on electrical tree evolving confirm experimental breakdown results. The sandwich-structured nanocomposite displays impressive high-temperature (150 °C) capacitive performances possessing meanwhile a high Eb of 5265.9 kV/cm, large discharged energy density (Ue) of 7.1 J/cm3, being about 6 times that of the commercial biaxially oriented polypropylene, and large charge-discharge efficiency (η) of 81.6 %, which exceeds obviously latest polymer and polymer composites in terms of overall energy storage performances. More encouragingly, it displays an ultrahigh power density of 15.63 MW/cm3 and ultrafast discharge rate of 19.2 ns at 150 °C, indicate its excellent application potential in high-temperature pulse power systems.

Development of ultrathin nanoflakes of Ni–Co LDH films by hydrothermal route for energy storage application

For energy storage systems, high capacitance, long cycling life, superior energy density, and ultrafast charge-discharge rates are important characteristics to meet the energy demands of various modern areas. Recently, the combination of Nickel (Ni) and Cobalt (Co) binary hydroxides has been recognized as a class of new materials due to their excellent electrochemical activity, high capacitance, excellent redox reversibility, spatial structure, and good electrical conductivity. Herein, Ni–Co layered double hydroxides (LDH) nanocomposites were prepared from different Ni–Co precursors under optimized preparation conditions by hydrothermal technique for supercapacitor application. As-obtained Ni–Co LDH exhibits an exceptionally high specific capacitance of 700.42 F/g was achieved at a current density of 1 A/g. Moreover, the Ni–Co LDH electrode showed a superior specific energy density of 19.69 Wh/kg and a specific power density of 2.8 Wh/kg. These excellent electrochemical results illustrate the potential of utilizing Ni–Co LDH materials for supercapacitor application and provide innovative direction for the development of future high-performance energy storage systems.

Multi-Frequency 3D Shear Wave Absolute Vibro-Elastography (S-WAVE) System for the Prostate.

This article describes a novel system for quantitative and volumetric measurement of tissue elasticity in the prostate using simultaneous multi-frequency tissue excitation. Elasticity is computed by using a local frequency estimator to measure the three-dimensional local wavelengths of steady-state shear waves within the prostate gland. The shear wave is created using a mechanical voice coil shaker which transmits simultaneous multi-frequency vibrations transperineally. Radio frequency data is streamed directly from a BK Medical 8848 transrectal ultrasound transducer to an external computer where tissue displacement due to the excitation is measured using a speckle tracking algorithm. Bandpass sampling is used that eliminates the need for an ultra-fast frame rate to track the tissue motion and allows for accurate reconstruction at a sampling frequency that is below the Nyquist rate. A roll motor with computer control is used to rotate the transducer and obtain 3D data. Two commercially available phantoms were used to validate both the accuracy of the elasticity measurements as well as the functional feasibility of using the system for in vivo prostate imaging. The phantom measurements were compared with 3D Magnetic Resonance Elastography (MRE), where a high correlation of 96% was achieved. In addition, the system has been used in two separate clinical studies as a method for cancer identification. Qualitative and quantitative results of 11 patients from these clinical studies are presented here. Furthermore, an AUC of 0.87±0.12 was achieved for malignant vs. benign classification using a binary support vector machine classifier trained with data from the latest clinical study with leave one patient out cross-validation.

Customization of an Ultrafast Thiol-Norbornene Photo-Cross-Linkable Hyaluronic Acid-Gelatin Bioink for Extrusion-Based 3D Bioprinting.

Light-based three-dimensional (3D) bioprinting has been widely studied in tissue engineering. Despite the fact that free-radical chain polymerization-based bioinks like hyaluronic acid methacrylate (HAMA) and gelatin methacryloyl (GelMA) have been extensively explored in 3D bioprinting, the thiol-ene hydrogel system has attracted increasing attention for its ability in building hydrogel scaffolds in an oxygen-tolerant and cell-friendly way. Herein, we report a superfast curing thiol-ene bioink composed of norbornene-modified hyaluronic acid (NorHA) and thiolated gelatin (GelSH) for 3D bioprinting. A new facile approach was first introduced in the synthesis of NorHA, which circumvented the cumbersome steps involved in previous works. Additionally, after mixing NorHA with macro-cross-linker GelSH, the customized NorHA/GelSH bioinks exhibited fascinating superiorities over the gold standard GelMA bioinks, such as an ultrafast curing rate (1-5 s), much lowered photoinitiator concentration (0.03% w/v), and flexible physical performances. Moreover, the NorHA/GelSH hydrogel greatly avoided excess ROS generation, which is important for the survival of the encapsulated cells. Last, compared with the GelMA scaffold, the 3D-printed NorHA/GelSH scaffold not only exhibited excellent cell viability but also guaranteed cell proliferation, revealing its superior bioactivity. In conclusion, the NorHA/GelSH system is a promising candidate for 3D bioprinting and tissue engineering applications.

Ecofriendly superhydrophobic fabrics for ultra-fast oil/water separation by self-assembly

The growing interest in superhydrophobic materials for oil/water separation has become evident. Concurrently, there exists a pressing requirement for superhydrophobic materials capable of achieving ultra-fast oil/water separation with an environmentally friendly, low-cost, and facile preparation strategy. Herein, an ecofriendly superhydrophobic fabric is prepared through a process involving self-assembly between iron ions and 1,3,5-benzene tricarboxylic acid (H3BTC), followed by hydrophobic modification of polydimethylsiloxane (PDMS). In this process, gallic acid (GA) undergoes self-polymerization and reacts with ethylenediamine (ED) by the Schiff base reaction to form polymers, which act as metal active sites before the self-assembly between iron ions and H3BTC takes place. The obtained superhydrophobic fabric with self-cleaning function features ultra-fast oil/water separation performance, with a flux of 32,527.18 ± 243.22 L m−2 h−1 and a separation efficiency of 99.87 ± 0.02 %. Moreover, the superhydrophobic fabric has good recyclability. Even after 30 times of oil/water separation, it still has ultra-fast separation rate and superhigh separation efficiency, with a flux of 20,678.17 ± 137.58 L m−2 h−1 and 99.47 ± 0.16 % separation efficiency. In addition, the superhydrophobic fabric maintains outstanding superhydrophobicity after treatment in the chemical or physical environment.

Achieving Ultrahigh Energy Storage Performance for NaNbO3-Based Lead-Free Antiferroelectric Ceramics via the Coupling of the Stable Antiferroelectric R Phase and Nanodomain Engineering.

NaNbO3(NN)-based lead-free eco-friendly antiferroelectric (AFE) ceramics with an extremely high maximum polarization (Pm) are believed to be a promising alternative to traditional lead-based ceramics. Nevertheless, the high energy dissipation resulting from the large polarization hysteresis, which arises from the AFE-ferroelectric (FE) phase transition, poses a great challenge to the application of this promising ceramic. Herein, an excellent recoverable energy storage density (Wrec) was attained by intentionally designing a (0.86 - x) NaNbO3-0.14CaTiO3-xBiMg2/3Nb1/3O3 (NN-CT-xBMN) relaxor antiferroelectric ceramic, attributed to the synergistic effect of the stable AFE R phase and nanodomain engineering to overcome the bottleneck. The obtained results illustrate that the inclusion of BMN causes the transition from AFE microdomains to nanodomains and stabilizes the relaxor AFE orthorhombic R phase, which generates a highly stable polarization field response with low hysteresis and delays the AFE-FE phase transition, thus improving energy storage density. As a consequence, a high Wrec of 5.41 J cm-3 with an excellent conversion efficiency η of 86.7% was obtained in the NN-CT-0.08BMN ceramic. Moreover, the NN-CT-0.08BMN ceramic exhibits superior stability in temperature (25-150 °C), frequency (1-600 Hz), and fatigue behavior (10°-104 cycles) together with a large current density (CD = 810 A cm-2), ultrahigh power density (PD = 118 MW cm-3), and ultrafast discharge rate (t0.9 < 0.7 μs). This superior energy storage density, coupled with outstanding stability, suggests that the NN-CT-0.08BMN ceramic has the potential to be a promising candidate for pulsed power applications and power electronics.

Near-field imaging and spectroscopy of terahertz resonators and metasurfaces [Invited

Terahertz (THz) metasurfaces have become a key platform for engineering light-matter interaction at THz frequencies. They have evolved from simple metallic resonator arrays into tunable and programmable devices, displaying ultrafast modulation rates and incorporating emerging quantum materials. The electrodynamics which govern metasurface operation can only be directly revealed at the scale of subwavelength individual metasurface elements, through sampling their evanescent fields. It requires near-field spectroscopy and imaging techniques to overcome the diffraction limit and provide spatial resolution down to the nanoscale. Through a series of case studies, this review provides an in-depth overview of recently developed THz near-field microscopy capabilities for research on metamaterials.

Efficient and fast remediation of soil contaminated by per- and polyfluoroalkyl substances (PFAS) by high-frequency heating

This study presents a novel thermal technology (high-frequency heating, HFH) for the decontamination of soil containing per- and polyfluoroalkyl substances (PFAS) and aqueous film-forming foams (AFFFs). Ultra-fast degradation of short-chain PFAS, long-chain homologs, precursors, legacy PFAS, emerging PFAS was achieved in a matter of minutes. The concentrations of PFAS and the soil type had a negligible impact on degradation efficiency, possibly due to the ultra-fast degradation rate overwhelming potential differences. Under the current HFH experiment setup, we achieved near-complete degradation (e.g., >99.9%) after 1 min for perfluoroalkyl carboxylic acids and perfluoroalkyl ether carboxylic acids and 2 min for perfluoroalkanesulfonic acids. Polyfluoroalkyl precursors in AFFFs were found to degrade completely within 1 min of HFH; no residual cationic, zwitterionic, anionic, or non-ionic intermediate products were detected following the treatment. The gaseous byproducts were considered. Most of gaseous organofluorine products of PFAS at low-and-moderate temperatures disappeared when temperatures reached 890 °C, which is in the temperature zone of HFH. For the first time, we demonstrated minimal loss of PFAS in water during the boiling process, indicating a low risk of PFAS entering the atmosphere with the water vapor. The findings highlight HFH its potential as a promising remediation tool for PFAS-contaminated soils.

Type-I CdS/ZnS Core/Shell Quantum Dot-Gold Heterostructural Nanocrystals for Enhanced Photocatalytic Hydrogen Generation.

Developing Type-I core/shell quantum dots is of great importance toward fabricating stable and sustainable photocatalysts. However, the application of Type-I systems has been limited due to the strongly confined photogenerated charges by the energy barrier originating from the wide-bandgap shell material. In this project, we found that through the decoration of Au satellite-type domains on the surface of Type-I CdS/ZnS core/shell quantum dots, such an energy barrier can be effectively overcome and an over 400-fold enhancement of photocatalytic H2 evolution rate was achieved compared to bare CdS/ZnS quantum dots. Transient absorption spectroscopic studies indicated that the charges can be effectively extracted and subsequently transferred to surrounding molecular substrates in a subpicosecond time scale in such hybrid nanocrystals. Based on density functional theory calculations, the ultrafast charge separation rates were ascribed to the formation of intermediate Au2S layer at the semiconductor-metal interface, which can successfully offset the energy confinement introduced by the ZnS shell. Our findings not only provide insightful understandings on charge carrier dynamics in semiconductor-metal heterostructural materials but also pave the way for the future design of quantum dot-based hybrid photocatalytic systems.

Superhigh and ultrafast removal of congo red and methylene blue in the evolution process of ferroan brucite with multiple mechanism

Ferroan brucite with different Fe2+ doping amount (MgFe(OH)2-x, x = 0.05, 0.1, 0.15, 0.2 and 0.3) were prepared for the removal of organic dyes from wastewater. In the presence of O2, MgFe(OH)2-0.3 could realize superhigh amount of removal (2069.16 mg/g) toward congo red (CR) and ultrafast removal rate toward methylene blue (MB), reaching equilibrium in about 5 min. Removal mechanism of MgFe(OH)2-0.3 for CR and MB was explored to verify the treatment nature. For CR, multiple removal mechanisms, such as interlayer immobilization/electrostatic attraction/hydrogen bonding and degradation were confirmed to coexist which accounted for 47.80% and 52.20% of the total removal amount. The degradation was highly related to the evolution of Fe2+ in MgFe(OH)2. While hydrogen bonding and degradation played major role in MB removal. The removal behavior of CR and MB in co-existing case and in presence of competitive ions were also measured. MgFe(OH)2-0.3 showed almost uninfluenced removal behavior toward CR and the reason was clarified by calculating the binding energy based on molecular simulation. Ferroan brucite not only showed excellent removal ability toward different kinds of dyes but also worked on heavy metals. This work provided an excellent strategy for application of ferroan brucite.

Fine‐Tuning Electrolyte Concentration and Metal–Organic Framework Surface toward Actuating Fast Zn2+ Dehydration for Aqueous Zn‐Ion Batteries

AbstractFunctional porous coating on zinc electrode is emerging as a powerful ionic sieve to suppress dendrite growth and side reactions, thereby improving highly reversible aqueous zinc ion batteries. However, the ultrafast charge rate is limited by the substantial cation transmission strongly associated with dehydration efficiency. Here, we unveil the entire dynamic process of solvated Zn2+ ions’ continuous dehydration from electrolyte across the MOF‐electrolyte interface into channels with the aid of molecular simulations, taking zeolitic imidazolate framework ZIF‐7 as proof‐of‐concept. The moderate concentration of 2 M ZnSO4 electrolyte being advantageous over other concentrations possesses the homogeneous water‐mediated ion pairing distribution, resulting in the lowest dehydration energy, which elucidates the molecular mechanism underlying such concentration adopted by numerous experimental studies. Furthermore, we show that modifying linkers on the ZIF‐7 surface with hydrophilic groups such as −OH or −NH2 can weaken the solvation shell of Zn2+ ions to lower the dehydration free energy by approximately 1 eV, and may improve the electrical conductivity of MOF. These results shed light on the ions delivery mechanism and pave way to achieve long‐term stable zinc anodes at high capacities through atomic‐scale modification of functional porous materials.

Fine-Tuning Electrolyte Concentration and Metal-Organic Framework Surface toward Actuating Fast Zn2+ Dehydration for Aqueous Zn-Ion Batteries.

Functional porous coating on zinc electrode is emerging as a powerful ionic sieve to suppress dendrite growth and side reactions, thereby improving highly reversible aqueous zinc ion batteries. However, the ultrafast charge rate is limited by the substantial cation transmission strongly associated with dehydration efficiency. Here, we unveil the entire dynamic process of solvated Zn2+ ions' continuous dehydration from electrolyte across the MOF-electrolyte interface into channels with the aid of molecular simulations, taking zeolitic imidazolate framework ZIF-7 as proof-of-concept. The moderate concentration of 2 M ZnSO4 electrolyte being advantageous over other concentrations possesses the homogeneous water-mediated ion pairing distribution, resulting in the lowest dehydration energy, which elucidates the molecular mechanism underlying such concentration adopted by numerous experimental studies. Furthermore, we show that modifying linkers on the ZIF-7 surface with hydrophilic groups such as -OH or -NH2 can weaken the solvation shell of Zn2+ ions to lower the dehydration free energy by approximately 1 eV, and may improve the electrical conductivity of MOF. These results shed light on the ions delivery mechanism and pave way to achieve long-term stable zinc anodes at high capacities through atomic-scale modification of functional porous materials.

Enhancing densification rate and the unusual 4H-SiC polytype stabilization in ultrafast high-temperature sintering of α-SiC

Novel Powder medium-based Ultrafast High-temperature Sintering (P-UHS) technique brings unexplored opportunities for the ultrarapid consolidation of large-sized and difficult-to-sinter ceramics with a complex shape. Herein, the P-UHS was demonstrated to be very effective means for the densification of large-sized α-SiC bulks (∼16 cm3) with boron and carbon additions under heating rates exceeding 1500 °C/min. Bulk ceramics with ∼97% density and homogenous microstructure were obtained within only 6 min. The ultrafast heating led to two orders of magnitude increase in the densification rate contributing to an energy saving of 90% if compared to conventional sintering process. In addition, the preferential 4H-SiC polytype stabilization was observed only when ultrafast heating rate was employed. The non-equilibrium transient chemistry and the ultrarapid shrinkage were considered as the major drivers for this unusual phenomenon.

Detector-trigger-based cardiac multiphase micro-CT imaging for small animals.

Micro-computed tomography is important in cardiac imaging for preclinical small animal models, but motion artifacts may appear due to the rapid heart rates. To avoid influence of motion artifacts, the prospective ECG gating schemes based on an X-ray source trigger have been investigated. However, due to the lack of pulsed X-ray exposure modes, high-resolution micro-focus X-ray sources do not support source triggering in most cases. To develop a fast-cardiac multiphase acquisition strategy using prospective ECG gating for micro-focus X-ray tubes with a continuous emission mode. The proposed detector-trigger-based prospective ECG gating acquisition scheme (DTB-PG) triggers the X-ray detector at the R peak of ECG, and then collects multiple phase projections of the heart in one ECG cycle by sequence acquisition. Cardiac multiphase images are reconstructed after performing the same acquisition in all views. The feasibility of this strategy was verified in multiphase imaging experiments of a phantom with 150 ms motion period and a mouse heart on a micro-focus micro-CT system with continuous emission mode. Using a high frame-rate CMOS detector, DTB-PG discriminates the positions of the motion phantom well in 10 different phases and enables to distinguish the changes in the cardiac volume of the mouse in different phases. The acquisition rate of DTB-PG is much faster than other prospective gating schemes as demonstrated by theoretical analysis. DTB-PG combines the advantages of prospective ECG gating strategies and X-ray detector-trigger mode to suppress motion artifacts, achieve ultra-fast acquisition rates, and relax hardware limitations.

Revealing the ultrafast spontaneous emission in plasmon-enhanced monolayer semiconductor nano-light sources

Nanoscale spontaneous light sources are promising alternatives to lasers for high-speed optical communications and interconnections through energy-efficient integrated circuits. Yet, developing the spontaneous light sources faster than lasers is hampered by the detection means (e.g., time-resolved fluorescence spectroscopy). Here, by coupling monolayer WSe2 to individual plasmonic nanocavities, we achieved an efficient spontaneous light source with potential ultrafast modulation bandwidth and superior brightness. The ultrafast radiative decay rates can be determined and derived solely from the experimental parameters by combining the coupling strength and the photoluminescence enhancement in a single nanocavity-WSe2 hybrid. As a result, the hybrid light source has a radiative lifetime down to 350 fs, indicating a potential modulation bandwidth up to 440 GHz, which is 10 times of the traditional semiconductor lasers. Furthermore, the quantum yield is enhanced by a factor of over 300-folds up to 20.8% through making full use of the highly confined nanocavity mode. The nanocavity-WSe2 hybrid we built provides a promising approach for constructing high-speed light-emitting devices.

Compressible polydopamine modified pomelo peel powder/poly(ethyleneimine)/κ-carrageenan aerogel with pH-tunable charge for selective removal of anionic and cationic dyes

In this work, a novel biomass-based aerogel, polydopamine decorated pomelo peel powder/polyethyleneimine/κ-carrageenan (PPEKC) aerogel, was developed for dye wastewater treatment. The as-prepared PPEKC aerogel possessed a robust structure and good compressible resilience. As expected, this aerogel presented remarkable efficacy in eliminating both anionic and cationic dyes. The experimental maximum adsorption capacities were 2016.7 mg g−1 for congo red (CR) at pH = 5 and 1176.6 mg g−1 for methylene blue (MEB) at pH = 11, following with ultra-fast adsorption rates. The adsorption kinetics followed the pseudo-second-order model. The adsorption isotherms exhibited a stronger alignment with the Langmuir isotherm model for CR at 308 K and MEB at 288, 298, 308 K. The Freundlich isotherm model yielded a suitable fit for the adsorption of CR at 288 and 298 K. Thermodynamic analyses indicated that the removal of CR and MEB was spontaneous and endothermic. The adsorption mechanisms involved electrostatic interactions, π-π interactions, and hydrogen bonds. Intriguingly, it could achieve bidirectional selective adsorption of anionic and cationic dyes in the designed pH values, due to pH-tunable surface charge. Additionally, it also exhibited favorable reusability and antibacterial activity. Therefore, the as-prepared PPEKC aerogel could be a promising biosorbent for dye wastewater treatment.

Two-dimensional vertical-lateral hybrid heterostructure for ultrasensitive photodetection and image sensing

Constructing heterostructures of two-dimensional (2D) materials is critical for boosting their photoelectric performances, enabling a promising route to meet the harsh requirement of next-generation optoelectronic devices. However, the practical application of currently-studied lateral and vertical heterostructures is usually limited by poor photocarrier generation and transport abilities, primarily due to their inherent imbalance of depletion region and interface area. To solve this obstacle, we herein report a novel 2D hybrid heterostructure of bismuth selenide/oxyselenide with the coexistence of lateral and vertical interfaces. The unique hybrid structure provides the heterostructure with a huge interface area and a wide depletion region for sufficient photocarrier generation and separation, significantly improving the overall optoelectronic performances of the device. Specifically, the resultant photodetectors exhibit a remarkably decreased dark current and ultrafast photoresponse rate (τrise = 50 μs and τdecay = 20 μs). Moreover, our photodetector demonstrates outstanding image sensing capability for recording various complex patterns with high resolution over a wide spectral range from ultraviolet, visible to near-infrared regions. Our research provides a highly promising route for designing and fabricating novel geometries of 2D heterostructures to realize diverse photoelectric applications.

Optimizing the energy storage performance of NaNbO3 ceramics by rare-earth-based composite perovskite Sm(Mg0.5Zr0.5)O3 modification

Researchers often improve the energy storage performance of NaNbO3 ceramics through doping with Bi-based composites. Recent studies have shown that rare-earth elements, such as La and Sm, can suppress remanent polarization. In this study, a (1-x )NaNbO3-x Sm(Mg0.5Zr0.5)O3 ceramic system was designed. Doping with Sm(Mg0.5Zr0.5)O3 (SMZ) increases the resistance, activation energy, and bandgap of NaNbO3 ceramics, improves the breakdown field strength, and optimizes the energy storage efficiency of NaNbO3 ceramics. In this study, 0.92NaNbO3-0.08 SMZ achieved an energy storage density of 4.3/cm3 and an energy storage efficiency of 85.6% at 560 kV/cm. When x = 0.15, the sample exhibited an ultrahigh breakdown field strength and energy storage efficiency (720 kV/cm and 91%, respectively). In addition, the 0.08 SMZ sample had an ultrafast release rate of t 0.9 (57 ns), high current density (777.1 A/cm2), and high power density (69.93 MW/cm3). It has practical application prospects in high-performance energy storage capacitors.

Surface Engineering of Fluorinated Graphene Nanosheets Enables Ultrafast Lithium/Sodium/Potassium Primary Batteries.

Fluorinated carbon (CFx ) is considered as a promising cathode material for lithium/sodium/potassium primary batteries with superior theoretical energy density. However, achieving high energy and power densities simultaneously remains a considerable challenge due to the strong covalency of the C-F bond in the highly fluorinated CFx . Herein, an efficient surface engineering strategy combining surface defluorination and nitrogen doping enables fluorinated graphene nanosheets (DFG-N) to possess controllable conductive nanolayers and reasonably regulated C-F bonds. The DFG-N delivers an unprecedented dual performance for lithium primary batteries with a power density of 77456W kg-1 and an energy density of 1067Wh kg-1 at an ultrafast rate of 50 C, which is the highest level reported to date. The DFG-N also achieves a record power density of 15 256 and 17 881W kg-1 at 10 C for sodium and potassium primary batteries, respectively. The characterization results and density functional theory calculations demonstrate that the excellent performance of DFG-N is attributed to surface engineering strategies that remarkably improve electronic and ionic conductivity without sacrificing the high fluorine content. This work provides a compelling strategy for developing advanced ultrafast primary batteries that combine ultrahigh energy density and power density.