Areal density and spatial resolution of high energy electron radiography

Ultrafast imaging tools are of great importance for determining the dynamic density distribution in high energy density(HED)matter.In this work,we designed a high energy electron radiography(HEER)system based on a linear electron accelerator to evaluate its capability for imaging HED matter.40 MeV electron beams were used to image an aluminum target to study the density resolution and spatial resolution of HEER.The results demonstrate a spatial resolution of tens of micrometers.The interaction of the beams with the target and the beam transport of the transmitted electrons are further simulated with EGS5 and PARMELA codes,with the results showing good agreement with the experimental resolution.Furthermore,the experiment can be improved by adding an aperture at the Fourier plane.

DD proton spectrum for diagnosing the areal density of imploded capsules on Shenguang Ⅲ prototype laser facility

The primary DD proton spectrum is used for diagnosing the fuel-shell areal density pR of imploded capsules on Shenguang Ⅲ （SG-Ⅲ） prototype laser facility for the first time. A charged particle spectrometer （CPS） with a CR39 nuclear track detector is used to measure the DD proton spectrum. The proton spectrum is determined from both the proton track and its size. A typical proton energy peak shift from 3.02 MeV to 2.6 MeV is observed in our experiment, which yields a maximum pR larger than 6 mg/cm2.

Room Temperature Synthesis of Vertically Aligned Amorphous Ultrathin NiCo-LDH Nanosheets Bifunctional Flexible Supercapacitor Electrodes

Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm^(-2)as cathode and anode at 2 mA cm^(-2),and 79.5%and 80%capacity have been preserved at 50 mA cm^(-2).In the meantime,they all showed excellent cycling performance with negligible change after>10000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm^(-2)and 0.352 mW cm^(-3)).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.

Graphene Nanoribbons Enhancing the Electronic Conductivity and Ionic Diffusion of Graphene Electrodes for High-Performance Microsupercapacitors

The electrochemical performance of microsupercapacitors with graphene electrodes is reduced by the issue of graphene sheets aggregation,which limits electrolyte ions penetration into electrode.Increasing the space between graphene sheets in electrodes facilitates the electrolyte ions penetration,but sacrifices its electronic conductivity which also influences the charge storage ability.The challenging task is to improve the electrodes’electronic conductivity and ionic diffusion simultaneously,boosting the device’s electrochemical performance.Herein,we experimentally realize the enhancement of both electronic conductivity and ionic diffusion from 2D graphene nanoribbons assisted graphene electrode with porous layer-uponlayer structure,which is tailored by graphene nanoribbons and self-sacrificial templates ethyl cellulose.The designed electrode-based device delivers a high areal capacitance of 71 mF cm^(-2)and areal energy density of 9.83μWh cm^(-2),promising rate performance,outstanding cycling stability with 97%capacitance retention after 20000 cycles,and good mechanical properties.The strategy paves the way for fabricating high-performance graphene-based MSCs.

3D printing of fast kinetics reconciled ultra-thick cathodes for high areal energy density aqueous Li–Zn hybrid battery

The limitation of areal energy density of rechargeable aqueous hybrid batteries(RAHBs)has been a significant longstanding problem that impedes the application of RAHBs in miniaturized energy storage.Constructing thick electrodes with optimized geometrical properties is a promising strategy for achieving high areal energy density,but the sluggish ion/electron transfer and poor mechanical stability,as well as the increased electrode thickness,itself present well-known problems.In this work,a 3D printing technique is introduced to construct an ultra-thick lithium iron phosphate(LFP)/carboxylated carbon nanotube(CNT)/carboxyl terminated cellulose nanofiber(CNF)composite electrode with uncompromised reaction kinetics for high areal energy density Li–Zn RAHBs.The uniformly dispersed CNTs and CNFs form continuous interconnected 3D networks that encapsulate LFP nanoparticles,guaranteeing fast electron transfer and efficient stress relief as the electrode thickness increases.Additionally,multistage ion diffusion channels generated from the hierarchical porous structure assure accelerated ion diffusion.As a result,LFP/Zn hybrid pouch cells assembled with 3D printed electrodes deliver a well-retained reversible gravimetric capacity of about 143.5 mAh g^(-1) at 0.5 C as the electrode thickness increases from 0.52 to 1.56 mm,and establish a record-high areal energy density of 5.25 mWh cm^(-2) with an impressive utilization of active material up to 30 mg cm^(-2) for an ultra-thick(2.08 mm)electrode,which outperforms almost all reported zinc-based hybrid-ion and single-ion batteries.This work opens up exciting prospects for developing high areal energy density energy storage devices using 3D printing.

Flexible quasi-solid-state zinc-ion hybrid supercapacitor based on carbon cloths displays ultrahigh areal capacitance

Over the past few years,the flexible quasi-solid-state zinc-ion hybrid supercapacitors(FQSS ZHSCs)have been found to be ideal for wearable electronics applications due to their high areal capacitance and energy density.The assembly of desirable ZHSCs devices that have promising practical applications is of high importance,whereas it is still challenging to assemble ZHSCs devices.In this study,a ZHSC that exhibited ultrahigh areal capacitance and high stability was developed by using an active carbon cloth(ACC)cathode,which could improve ionic adsorption.The as-obtained ACC cathode had an energy storage mechanism due to the electrical double-layer capacitive behavior of Zn^(2+),which was accompanied by the dissolution/deposition of Zn_(4)SO_(4)(OH)6·5H2O.The ACC//Zn@ACC ZHSC device exhibited an areal capacitance of 2437 mF cm^(−2)(81 F cm^(−3),203 F g^(-1) under the mass of ACC with∼12 mg cm^(−2))at 1 mA cm^(−2),an areal energy density of 1.354 mWh cm^(−2) at 1 mW cm^(−2),as well as high stability(with an insignificant capacitance decline after 20000 cycles),which was demonstrated to outperform the existing ZHSCs.Furthermore,the assembled flexible device still had competitive capacitance,energy density and service life when integrated into a FQSS ZHSC.When applied in practice,the device could achieve high mechanical flexibility,wearable stability and output.This study can inspire the development of the FQSS ZHSC device to satisfy the demands for wearable energy storage devices with high performance.

Enhancing electrolyte ion diffusion via direct ink writing pillar array structure of graphene electrodes for high-performance microsupercapacitors

The graphene-based microsupercapacitors(MSCs)suffer from graphene aggregation issue in electrodes.It reduces the electrolyte ions transportation in the electrodes to degrade the charge storage ability of MSCs,hampering their practical application.Increasing the electrolyte ions transportation in the electrodes can boost the charge storage ability of MSCs.Herein,we design and experimentally realize pillar array structure of graphene electrodes for MSCs by direct ink writing technology.The graphene electrodes with pillar array structure increase the contact area with electrolyte and short the electrolyte ions transport path,facilitating electrolyte ions transport in electrodes.The MSCs exhibit high areal capacitance of 25.67 mF·cm^(−2),high areal energy density of 20.54μWh·cm^(−2),and high power density of 1.45 mW·cm^(−2).One single MSCs can power timer for 10 min and pressure sensor more than 160 min,showing high practical application possibility.This work provides a new avenue for developing high performance MSCs.