查看更多>>摘要：Optimizing the high-temperature energy storage characteristics of energy storage dielectrics is of great significance for the development of pulsed power devices and power control systems.Selecting a polymer with a higher glass transition temperature(Tg)as the matrix is one of the effective ways to increase the upper limit of the polymer operating temperature.However,current high-Tg polymers have limitations,and it is difficult to meet the demand for high-temperature energy storage dielectrics with only one polymer.For example,polyetherimide has high-energy storage efficiency,but low breakdown strength at high temperatures.Polyimide has high corona resistance,but low high-temperature energy storage efficiency.In this work,combining the advantages of two polymer,a novel high-Tg polymer fiber-reinforced microstructure is designed.Polyimide is designed as extremely fine fibers distributed in the composite dielectric,which will facilitate the reduction of high-temperature conductivity loss for polyimide.At the same time,due to the high-temperature resistance and corona resistance of polyimide,the high-temperature breakdown strength of the composite dielectric is enhanced.After the polyimide content with the best high-temperature energy storage characteristics is determined,molecular semiconductors(ITIC)are blended into the polyimide fibers to further improve the high-temperature efficiency.Ultimately,excellent high-temperature energy storage properties are obtained.The 0.25 vol％ITIC-polyimide/polyetherimide composite exhibits high-energy density and high discharge efficiency at 150 ℃(2.9 J cm-3,90％)and 180 ℃(2.16 J cm-3,90％).This work provides a scalable design idea for high-performance all-organic high-temperature energy storage dielectrics.
查看更多>>摘要：How to achieve synergistic improvement of permittivity(er)and breakdown strength(Eb)is a huge challenge for polymer dielectrics.Here,for the first time,the π-conjugated comonomer(MHT)can simultaneously promote the er and Eb of linear poly(methyl methacrylate)(PMMA)copolymers.The PMMA-based random copolymer films(P(MMA-co-MHT)),block copolymer films(PMMA-b-PMHT),and PMMA-based blend films were prepared to investigate the effects of sequential structure,phase separation structure,and modification method on dielectric and energy storage properties of PMMA-based dielectric films.As a result,the random copolymer P(MMA-co-MHT)can achieve a maximum εr of 5.8 at 1 kHz owing to the enhanced orientation polarization and electron polarization.Because electron injection and charge transfer are limited by the strong electrostatic attraction ofπ-conjugated benzophenanthrene group analyzed by the density functional theory(DFT),the discharge energy density value of P(MMA-co-PMHT)containing 1 mol％MHT units with the efficiency of 80％reaches 15.00 J cm-3 at 872 MV m-1,which is 165％higher than that of pure PMMA.This study provides a simple and effective way to fabricate the high performance of polymer dielectrics via copolymerization with the monomer of P-type semi-conductive polymer.
查看更多>>摘要：Herein,we report the design,fabrication,and performance of two wireless energy harvesting devices based on highly flexible graphene macroscopic films(FGMFs).We first demonstrate that benefiting from the high conductivity of up to 1 × 106 S m-1 and good resistive stability of FGMFs even under extensive bending,the FGMFs-based rectifying circuit(GRC)exhibits good flexibility and RF-to-DC efficiency of 53％at 2.1 GHz.Moreover,we further expand the application of FGMFs to a flexible wideband monopole rectenna and a 2.45 GHz wearable rectenna for harvesting wireless energy.The wideband rectenna at various bending conditions produces a maximum conversion efficiency of 52％,46％,and 44％at the 5th Generation(5G)2.1 GHz,Industrial Long-Term Evolution(LTE)2.3 GHz,and Scientific Medical(ISM)2.45 GHz,respectively.A 2.45 GHz GRC is optimized and integrated with an AMC-backed wearable antenna.The proposed 2.45 GHz wearable rectenna shows a maximum conversion efficiency of 55.7％.All the results indicate that the highly flexible graphene-film-based rectennas have great potential as a wireless power supplier for smart Internet of Things(loT)applications.
Andrew MartinDrew LilleyRavi PrasherSumanjeet Kaur...
326-333页
查看更多>>摘要：Thermal energy storage(TES)solutions offer opportunities to reduce energy consumption,greenhouse gas emissions,and cost.Specifically,they can help reduce the peak load and address the intermittency of renewable energy sources by time shifting the load,which are critical toward zero energy buildings.Thermochemical materials(TCMs)as a class of TES undergo a solid-gas reversible chemical reaction with water vapor to store and release energy with high storage capacities(600 kWh m-3)and negligible self-discharge that makes them uniquely suited as compact,stand-alone units for daily or seasonal storage.However,TCMs suffer from instabilities at the material(salt particles)and reactor level(packed beds of salt),resulting in poor multi-cycle efficiency and high-levelized cost of storage.In this study,a model is developed to predict the pulverization limit or Rcrit of various salt hydrates during thermal cycling.This is critical as it provides design rules to make mechanically stable TCM composites as well as enables the use of more energy-efficient manufacturing process(solid-state mixing)to make the composites.The model is experimentally validated on multiple TCM salt hydrates with different water content,and effect of Rcrit on hydration and dehydration kinetics is also investigated.
查看更多>>摘要：Electrocatalysis enables the industrial transition to sustainable production of chemicals using abundant precursors and electricity from renewable sources.De-centralized production of hydrogen peroxide(H2O2)from water and oxygen of air is highly desirable for daily life and industry.We report an effective electrochemical refinery(e-refinery)for H2O2 by means of electrocatalysis-controlled comproportionation reaction(2HO+o → 2HO),feeding pure water and oxygen only.Mesoporous nickel(Ⅱ)oxide(NiO)was used as electrocatalyst for oxygen evolution reaction(OER),producing oxygen at the anode.Conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)drove the oxygen reduction reaction(ORR),forming H2O2 on the cathode.The reactions were evaluated in both half-cell and device configurations.The performance of the H2O2 e-refinery,assembled on anion-exchange solid electrolyte and fed with pure water,was limited by the unbalanced ionic transport.Optimization of the operation conditions allowed a conversion efficiency of 80％.
查看更多>>摘要：As an emerging technology to convert environmental high-entropy energy into electrical energy,triboelectric nanogenerator(TENG)has great demands for further enhancing the service lifetime and output performance in practical applications.Here,an ultra-robust and high-performance rotational triboelectric nanogenerator(R-TENG)by bearing charge pumping is proposed.The R-TENG composes of a pumping TENG(P-TENG),an output TENG(O-TENG),a voltage-multiplying circuit(VMC),and a buffer capacitor.The P-TENG is designed with freestanding mode based on a rolling ball bearing,which can also act as the rotating mechanical energy harvester.The output low charge from the P-TENG is accumulated and pumped to the non-contact O-TENG,which can simultaneously realize ultralow mechanical wear and high output performance.The matched instantaneous power of R-TENG is increased by 32 times under 300 r/min.Furthermore,the transferring charge of R-TENG can remain 95％during 15 days(6.4 × 106 cycles)continuous operation.This work presents a realizable method to further enhance the durability of TENG,which would facilitate the practical applications of high-performance TENG in harvesting distributed ambient micro mechanical energy.
Talshyn BegildayevaJayaraman TheerthagiriSeung Jun LeeAhreum Min...
350-358页
查看更多>>摘要：Here,furfural oxidation was performed to replace the kinetically sluggish O2 evolution reaction(OER).Pt-Co3O4 nanospheres were developed via pulsed laser ablation in liquid(PLAL)in a single step for the paired electrocatalysis of an H2 evolution reaction(HER)and furfural oxidation reaction(FOR).The FOR afforded a high furfural conversion(44.2％)with a major product of 2-furoic acid after a 2-h electrolysis at 1.55 V versus reversible hydrogen electrode in a 1.0-M KOH/50-mM furfural electrolyte.The Pt-Co3O4 electrode exhibited a small overpotential of 290 mV at 10 mA cm-2.As an anode and cathode in an electrolyzer system,the Pt-Co3O4 electrocatalyst required only a small applied cell voltage of～1.83 V to deliver 10 mA cm-2,compared with that of the pure water electrolyzer(OER||HER,～1.99 V).This study simultaneously realized the integrated production of energy-saving H2 fuel at the cathode and 2-furoic acid at the anode.
查看更多>>摘要：Here,a novel fabrication method for making free-standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass-derived hydrogels is presented.In situ formed flower-like CaCO3 molecularly embedded within the hydrogel network regulated the pore structure during in situ mineralization assisted one-step activation graphitization(iMAG),while the intrinsic structural integrity of the carbon aerogels was maintained.The homogenously distributed minerals simultaneously acted as a hard template,activating agent,and graphitization catalyst.The decomposition of the homogenously distributed CaCO3 during iMAG followed by the etching of residual CaO through a mild acid washing endowed a robust carbon aerogel with high porosity and excellent electrochemical performance.At 0.5 mA cm-2,the gravimetric capacitance increased from 0.01 F g-1 without mineralization to 322 F g-1 with iMAG,which exceeds values reported for any other free-standing or powder-based biomass-derived carbon electrodes.An outstanding cycling stability of～104％after 1000 cycles in 1 M HClO4 was demonstrated.The assembled symmetric supercapacitor device delivered a high specific capacitance of 376 F g-1 and a high energy density of 26 W h kg-1 at a power density of 4000 W kg-1,with excellent cycling performance(98.5％retention after 2000 cycles).In combination with the proposed 3D printed mold-assisted solution casting(3DMASC),iMAG allows for the generation of free-standing carbon aerogel architectures with arbitrary shapes.Furthermore,the novel method introduces flexibility in constructing free-standing carbon aerogels from any ionically cross-linkable biopolymer while maintaining the ability to tailor the design,dimensions,and pore size distribution for specific energy storage applications.
查看更多>>摘要：Hyperfluorescent organic light-emitting diodes(HF-OLEDs)approach has made it possible to achieve excellent device performance and color purity with low roll-off using noble-metal-free pure organic emitter.Despite significant progress,the performance of HF-OLEDs is still unsatisfactory due to the existence of a competitive dexter energy transfer(DET)pathway.In this contribution,two boron dipyrromethene(BODIPY)-based donor-acceptor emitters(BDP-C-Cz and BDP-N-Cz)with hybridized local and charge transfer characteristics(HLCT)are introduced in the HF-OLED to suppress the exciton loss by dexter mechanism,and a breakthrough performance with low-efficiency roll-off(0.3％)even at high brightness(1000 cd m-2)is achieved.It is demonstrated that the energy loss via the DET channel can be suppressed in HF-OLEDs utilizing the HLCT emitter,as the excitons from the dark triplet state of such emitters are funneled to its emissive singlet state following the hot-exciton mechanism.The developed HF-OLED device has realized a good maximum external quantum efficiency(EQE)of 19.25％at brightness of 1000 cd m-2 and maximum luminance over 60 000 cd m-2,with an emission peak at 602 nm and Commission International de L'Eclairage(CIE)coordinates(0.57,0.41),which is among the best-achieved results in solution-processed HF-OLEDs.This work presents a viable methodology to suppress energy loss and achieve high performance in the HF-OLEDs.
查看更多>>摘要：This paper reports a multifunctional magnetic-photoelectric laminate device based on the integration of spintronic material(La0.7Sr0.3MnO3)and multiferroic(Ni-doped BiFeO3),in which the repeatable modulation effect on the photoelectric properties were achieved by applying external magnetic fields.More obviously,photocurrent density(J)of the laminate was largely enhanced,the change rate of J up to 287.6％is obtained.This sensing function effect should be attributed to the low-field magnetoresistance effect in perovskite manganite and the scattering of spin photoelectron in multiferroic material.The laminate perfectly combines the functions of sensor and controller,which can not only reflect the intensity of environmental magnetic field,but also modulate the photoelectric conversion performance.This work provides an alternative and facile way to realize multi-degree-of-freedom control for photoelectric conversion performances and lastly miniaturize multifunction device.
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