High Density 3D Carbon Tube Nanoarray Electrode Boosting the Capacitance of Filter Capacitor

Electric double-layer capacitors(EDLCs)with fast frequency response are regarded as small-scale alternatives to the commercial bulky aluminum electrolytic capacitors.Creating carbon-based nanoarray electrodes with precise alignment and smooth ion channels is crucial for enhancing EDLCs’performance.However,controlling the density of macropore-dominated nanoarray electrodes poses challenges in boosting the capacitance of line-filtering EDLCs.Herein,a simple technique to finely adjust the vertical-pore diameter and inter-spacing in three-dimensional nanoporous anodic aluminum oxide(3D-AAO)template is achieved,and 3D compactly arranged carbon tube(3D-CACT)nanoarrays are created as electrodes for symmetrical EDLCs using nanoporous 3D-AAO template-assisted chemical vapor deposition of carbon.The 3D-CACT electrodes demonstrate a high surface area of 253.0 m^(2) g^(−1),a D/G band intensity ratio of 0.94,and a C/O atomic ratio of 8.As a result,the high-density 3D-CT nanoarray-based sandwich-type EDLCs demonstrate a record high specific areal capacitance of 3.23 mF cm^(-2) at 120 Hz and exceptional fast frequency response due to the vertically aligned and highly ordered nanoarray of closely packed CT units.The 3D-CT nanoarray electrode-based EDLCs could serve as line filters in integrated circuits,aiding power system miniaturization.

A Lightweight, Adhesive, Dual-Functionalized Over-Coating Interphase Toward Ultra-Stable High-Current Density Lithium Metal Anodes

Coherent manipulation of the lithium plating pattern is at the heart of the safe operation of metallic anodes in the battery technologies. In this article,a lightweight (~0.3 mg cm^(-2)), dual-functionalized carbon spheres are anchored onto the Cu foil as the interfacial protective layer via the chelation process of the catechol groups in the polydopamine precursor and the copper foil. The dual-functionalized carbon spheres exhibit the intriguing complementary features:Lithiophilic nitrogen dopants favor the Li+ion absorption and mitigate the nucleation barrier, while the micro/mesopore reservoir spatially homogenizes the ion flux distribution, confining the metallic propagation without dendrite-like protrusions. The metallic anode exhibits an ultra-stable plating/stripping process for 1 400 hr with the average Coulombic efficiency of ~99%. A full-cell prototype is constructed by pairing the N-doped carbon spheres on the bare Cu (NCS-Cu) electrode with the high-mass-loading LiVPO4F (12.5 mg cm^(-2)) cathode that can deliver a high energy density of 421.2 Wh kg^(-1) with the highest power density of 2106 W kg^(-1) to promise the anode use for high-power/energy-dense metallic batteries.

Assembly and Applications of Carbon Nanotube Thin Films

The ultimate goal of current research on carbon nanotubes （CNTs） is to make breakthroughs that advance nanotechnological applications of bulk CNT materials. Especially, there has been growing interest in CNT thin films because of their unique and usually enhanced properties and tremendous potential as components for use in nano-electronic and nano-mechanical device applications or as structural elements in various devices. If a synthetic or a post processing method can produce high yield of nanotube thin films, these structures will provide tremendous potential for fundamental research on these devices. This review will address the synthesis, the post processing and the device applications of self-assembled nanotube thin films.

Molecular investigation on the compatibility of epoxy resin with liquid oxygen

Conventional fiber reinforced plastics(FRPs)have compatibility issues with solid oxygen while used as a fuel tank,which might cause combustion and explosion.To study the compatibility of different epoxy resins with liquid oxygen,molecular dynamics was used to simulate the phase changes of cross-linked epoxy resins under the impact of solid oxygen.Three curing resin systems,which are bisphenol A epoxy resin(DGEBA),bisphenol F epoxy resin(DGEBF),and tetrahydrophthalate diglycidyl ester(epoxy resin 711),are modeled to investigate the rational material system for the application of fuel tanks in launching vehicles.The simulation results show that the order of solid oxygen compatibility of these epoxy resins is DGEBA>DGEBF>epoxy resin 711 at the same density of crosslinking.The selection of curing agent also has an impact on the compatibility,with the same epoxy,diaminodiphenyl methane(DDM)has more advanced performance comparing to diaminodiphenyl sulfone(DDS).

Regulating electrodeposition behavior through enhanced mass transfer for stable lithium metal anodes

Electrode process kinetics is a key part that determines the morphology of metal electrodeposition.However,the liquid-phase mass transfer process and its effect on lithium(Li)metal electrodeposition are still poorly understood.Herein,the effect of mass transfer on the electrodeposition behavior of Li metal is explored.Experiments and COMSOL Multiphysics simulations reveal that the enhanced mass transfer,which is induced by ultrasonic wave,can homogenize the ion flow on the surface of electrode to obtain uniform Li nucleation.Meanwhile,the rapid mass transfer of Li^(+)provides sufficient cations around the germinated Li to avoid preferential growth of Li in a specific direction.Based on the simultaneous regulation of nucleation and growth behavior,a smooth and compact Li deposits can be achieved,which exhibit a small polarization voltage during repeated Li plating/striping and a considerably enhanced cyclability.This work enriches the fundamental understanding of Li electrodeposition without dendrite structure and affords fresh guidance to develop dendrite-free metal anodes for metal-based batteries.

Understanding the Coffee ring Effect on Self-discharge Behavior of Printed micro-Supercapacitors

Printed micro-supercapacitor exhibits its flexibility in geometry design and integration,showing unprecedented potential in powering the internet of things and portable devices.However,the printing process brings undesired processing defects(e.g.,coffee ring effect),resulting in severe self-discharge of the printed micro-supercapacitors.The impact of such problems on device performance is poorly understood,limiting further development of microsupercapacitors.Herein,by analyzing the self-discharge behavior of fully printed micro-supercapacitors,the severe self-discharge problem is accelerated by the ohmic leakage caused by the coffee ring effect on an ultrathin polymer electrolyte.Based on this understanding,the coffee ring effect was successfully eradicated by introducing graphene oxide in the polymer electrolyte,achieving a decline of 99%in the self-discharge rate.Moreover,the micro-supercapacitors with uniformly printed polymer electrolyte present 7.64 F cm^(-3)volumetric capacitance(14.37 mF cm^(-2)areal capacitance),exhibiting about 50%increase compared to the one without graphene oxide addition.This work provides a new insight to understand the relationship between processing defects and device performance,which will help improve the performance and promote the application of printed micro-supercapacitors.

Ultrahigh-power electrochemical double-layer capacitors based on structurally integrated 3D carbon tube arrays

The rational design of electrodes is the key to achieving ultrahigh-power performance in electrochemical energy storage devices.Recently,we have constructed well-organized and integrated three-dimensional(3D)carbon tube(CT)grids(3D-CTGs)using a 3D porous anodic aluminum oxide template-assisted method as electrodes of electrical double-layer capacitors(EDLCs),showing excellent frequency response performance.The unique design warrants fast ion migration channels,excellent electronic conductivity,and good structural stability.This study achieved one of the highest carbon-based ultrahigh-power EDLCs with the 3D-CTG electrodes,resulting in ultrahigh power of 437 and 1708 W·cm−3 with aqueous and organic electrolytes,respectively.Capacitors constructed with these electrodes would have important application prospects in the ultrahigh-power output.The rational design and fabrication of the 3D-CTGs electrodes have demonstrated their capability to build capacitors with ultrahighpower performance and open up new possibilities for applications requiring high-power output.

Mechanical properties of nanocomposites reinforced by carbon nanotube sponges

Carbon nanotube(CNT)sponge exhibits unique porous and hierarchical structure that are beneficial to the design of ultralight and tough composites.In this study,CNT sponges(undoped and boron doped)reinforced polydimethylsiloxane(PDMS)composites were fabricated.Mechanical properties of the composite,including compressive modulus,rate-dependent modulus,stress relaxation behaviors,dynamic viscoelastic properties,and their dependency on temperature,were systematically investigated.A micromechanical model,Mori-Tanaka model,was validated to describe the mechanical behaviors of CNT sponge reinforced composites.By coupling with boron-doped CNT sponge,PDMS composites showed remarkable improvement of mechanical properties,including compressive modulus(70%),viscous modulus(243%)and damping capacity(50%).Such reinforcement effects can be controlled by the morphology of CNT sponges,as the boron-doped and undoped nanocomposites showed distinct viscoelastic behaviors.The results proved that CNT sponge reinforcement is a promising strategy to develop engineering composites with both outstanding mechanical stiffness and controllable viscoelastic performances.