查看更多>>摘要：Two-dimensional materials have been widely used to tune the growth and energy-level alignment of perovskites.However,their incomplete passivation and chaotic usage amounts are not conducive to the preparation of high-quality perovskite films.Herein,we succeeded in obtaining higher-quality CsPbBr3 films by introducing large-area monolayer graphene as a stable physical overlay on top of TiO2 substrates.Benefiting from the inert and atomic smooth graphene surface,the CsPbBr3 film grown on top by the van der Waal epitaxy has higher crystallinity,improved(100)orientation,and an average domain size of up to 1.22 pm.Meanwhile,a strong downward band bending is observed at the graphene/perovskite interface,improving the electron extraction to the electron transport layers(ETL).As a result,perovskite film grown on graphene has lower photoluminescence(PL)intensity,shorter carrier lifetime,and fewer defects.Finally,a photovoltaic device based on epitaxy CsPbBr3 film is fabricated,exhibiting power conversion efficiency(PCE)of up to 10.64％and stability over 2000 h in the air.
查看更多>>摘要：The emergence of polymerized small molecule acceptors(PSMAs)has significantly improved the performance of all-polymer solar cells(all-PSCs).However,the pace of device engineering lacks behind that of materials development,so that a majority of the PSMAs have not fulfilled their potentials.Furthermore,most high-performance all-PSCs rely on the use of chloroform as the processing solvent.For instance,the recent high-performance PSMA,named PJ1-y,with high LUMO,and HOMO levels,could only achieve a PCE of 16.1％with a high-energy-level donor(JD40)using chloroform.Herein,we present a methodology combining sequential processing(SqP)with the addition of 0.5％wt PC71BM as a solid additive(SA)to achieve an impressive efficiency of 18.0％for all-PSCs processed from toluene,an aromatic hydrocarbon solvent.Compared to the conventional blend-casting(BC)method whose best efficiency(16.7％)could only be achieved using chloroform,the SqP method significantly boosted the device efficiency using toluene as the processing solvent.In addition,the donor we employ is the classic PM6 that has deeper energy levels than JD40,which provides low energy loss for the device.We compare the results with another PSMA(PYF-T-o)with the same method.Finally,an improved photostability of the SqP devices with the incorporation of SA is demonstrated.
查看更多>>摘要：Supercapacitors based on two-dimensional MXene(Ti3C2Tz)have shown extraordinary performance in ultrathin electrodes with low mass loading,but usually there is a significant reduction in high-rate performance as the thickness increases,caused by increasing ion diffusion limitation.Further limitations include restacking of the nanosheets,which makes it challenging to realize the full potential of these electrode materials.Herein,we demonstrate the design of a vertically aligned MXene hydrogel composite,achieved by thermal-assisted self-assembled gelation,for high-rate energy storage.The highly interconnected MXene network in the hydrogel architecture provides very good electron transport properties,and its vertical ion channel structure facilitates rapid ion transport.The resulting hydrogel electrode show excellent performance in both aqueous and organic electrolytes with respect to high capacitance,stability,and high-rate capability for up to 300 pm thick electrodes,which represents a significant step toward practical applications.
查看更多>>摘要：Printed micro-supercapacitors(MSCs)have shown broad prospect in flexible and wearable electronics.Most of previous studies focused on printing the electrochemically active materials paying less attention to other key components like current collectors and electrolytes.This study presents an all-printing strategy to fabricate in-plane flexible and substrate-free MSCs with hierarchical encapsulation.This new type of"all-in-one"MSC is constructed by encapsulating the in-plane interdigital current collectors and electrodes within the polyvinyl-alcohol-based hydrogel electrolyte via sequential printing.The bottom electrolyte layer of this fully printed MSCs helps protect the device from the limitation of conventional substrate,showing excellent flexibility.The MSCs maintain a high capacitance retention of 96.84％even in a completely folded state.An optimal electrochemical performance can be achieved by providing ample and shorter transport paths for ions.The MSCs using commercial activated carbon as the active material are endowed with a high specific areal capacitance of 1892.90 mF cm-2 at a current density of 0.3 mA cm-2,and an outstanding volumetric energy density of 9.20 mWh cm-3 at a volumetric power density of 6.89 mW cm-3.For demonstration,a thermo-hygrometer is stably powered by five MSCs which are connected in series and wrapped onto a glass rod.This low-cost and versatile all-printing strategy is believed to diversify the application fields of MSCs with high capacitance and excellent flexibility.
查看更多>>摘要：Energy density,the Achilles'heel of aqueous supercapacitors,is simultaneously determined by the voltage window and specific capacitance of the carbon materials,but the strategy of synchronously boosting them has rarely been reported.Herein,we demonstrate that the rational utilization of the interaction between redox mediators(RMs)and carbon electrode materials,especially those with rich intrinsic defects,contributes to extended potential windows and more stored charges concurrently.Using 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxyl(4OH-TEMPO)and intrinsic defect-rich carbons as the RMs and electrode materials,respectively,the potential window and capacitance are increased by 67％and sixfold in a neutral electrolyte.Moreover,this strategy could also be applied to alkaline and acid electrolytes.The first-principle calculation and experimental results demonstrate that the strong interaction between 4OH-TEMPO and defect-rich carbons plays a key role as preferential adsorbed RMs may largely prohibit the contact of free water molecules with the electrode materials to terminate the water splitting at elevated potentials.For the RMs offering weaker interaction with the electrode materials,the water splitting still proceeds with a thus sole increase of the stored charges.The results discovered in this work could provide an alternative solution to address the low energy density of aqueous supercapacitors.
查看更多>>摘要：Exploring a novel strategy for large-scale production of battery-type Ni(OH)2-based composites,with excellent capacitive performance,is still greatly challenging.Herein,we developed a facile and cost-effective strategy to in situ grow a layer of Ni(OH)2/Ti3C2Tx composite on the nickel foam(NF)collector,where Ti3C2Tx is not only a conductive component,but also a catalyst that accelerates the oxidation of NF to Ni(OH)2.Detailed analysis reveals that the crystallinity,morphology,and electronic structure of the integrated electrode can be tuned via the electrochemical activation,which is beneficial for improving electrical conductivity and redox activity.As expected,the integrated electrode shows a specific capacity of 1.09 C cm-2 at 1 mA cm-2 after three custom activation cycles and maintains 92.4％of the initial capacity after 1500 cycles.Moreover,a hybrid supercapacitor composed of Ni(OH)2/Ti3C2Tx/NF cathode and activated carbon anode provides an energy density of 0.1 mWh cm-2 at a power density of 0.97 mW cm-2,and excellent cycling stability with about 110％capacity retention rate after 5000 cycles.This work would afford an economical and convenient method to steer commercial Ni foam into advanced Ni(OH)2-based composite materials as binder-free electrodes for hybrid supercapacitors.
查看更多>>摘要：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-upon-layer 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 9.83 μWh cm-2,promising rate performance,outstanding cycling stability with 97％capacitance retention after 20 000 cycles,and good mechanical properties.The strategy paves the way for fabricating high-performance graphene-based MSCs.
查看更多>>摘要：Sodium-ion capacitors(SICs)have great potential in energy storage due to their low cost,the abundance of Na,and the potential to deliver high energy and power simultaneously.This article demonstrates a template-assisted method to induce graphitic nanodomains and micro-mesopores into nitrogen-doped carbons.This study elucidates that these graphitic nanodomains are beneficial for Na+storage.The obtained N-doped carbon(As8Mg)electrode achieved a reversible capacity of 254 mA h g-1 at 0.1 A g-1.Moreover,the As8Mg-based SIC device achieves high combinations of power/energy densities(53 W kg-1 at 224 Wh kg-1 and 10 410 W kg-1 at 51 Wh kg-1)with outstanding cycle stability(99.7％retention over 600 cycles at 0.2 A g-1).Our findings provide insights into optimizing carbon's microstructure to boost sodium storage in the pseudocapacitive mode.
查看更多>>摘要：The development of self-charging supercapacitor power cells(SCSPCs)has profound implications for smart electronic devices used in different fields.Here,we epitaxially electrodeposited Mo-and Fe-codoped MnO2 films on piezoelectric ZnO nanoarrays(NAs)grown on the flexible carbon cloth(denoted ZnO@Mo-Fe-MnO2 NAs).A self-charging supercapacitor power cell device was assembled with the Mo-and Fe-codoped MnO2 nanoarray electrode and poly(vinylidenefluoride-co-trifluoroethylene)(PVDF-Trfe)piezoelectric film doped with BaTiO3(BTO)and carbon nanotubes(CNTs)(denoted PVDF-Trfe/CNTs/BTO).The self-charging supercapacitor power cell device exhibited an energy density of 30 μWh cm 2 with a high power density of 40 mW cm-2 and delivered an excellent self-charging performance of 363 mV(10 N)driven by both the piezoelectric ZnO nanoarrays and the poly(vinylidenefluoride-co-trifluoroethylene)piezoelectric film doped with BaTiO3 and carbon nanotubes.More intriguingly,the device could also be self-charged by 184 mV due to residual stress alone and showed excellent energy conversion efficiency and low self-discharge rate.This work illustrates for the first time the self-charging mechanism involving electrolyte ion migration driven by both electrodes and films.A comprehensive analysis strongly confirmed the important contribution of the piezoelectric ZnO nanoarrays in the self-charging process of the self-charging supercapacitor power cell device.This work provides novel directions and insights for the development of self-charging supercapacitor power cells.
查看更多>>摘要：Traditional heat conductive epoxy composites often fall short in meeting the escalating heat dissipation demands of large-power,high-frequency,and high-voltage insulating packaging applications,due to the challenge of achieving high thermal conductivity(k),desirable dielectric performance,and robust thermomechanical properties simultaneously.Liquid crystal epoxy(LCE)emerges as a unique epoxy,exhibiting inherently high k achieved through the self-assembly of mesogenic units into ordered structures.This characteristic enables liquid crystal epoxy to retain all the beneficial physical properties of pristine epoxy,while demonstrating a prominently enhanced k.As such,liquid crystal epoxy materials represent a promising solution for thermal management,with potential to tackle the critical issues and technical bottlenecks impeding the increasing miniaturization of microelectronic devices and electrical equipment.This article provides a comprehensive review on recent advances in liquid crystal epoxy,emphasizing the correlation between liquid crystal epoxy's microscopic arrangement,organized mesoscopic domain,k,and relevant physical properties.The impacts of LC units and curing agents on the development of ordered structure are discussed,alongside the consequent effects on the k,dielectric,thermal,and other properties.External processing factors such as temperature and pressure and their influence on the formation and organization of structured domains are also evaluated.Finally,potential applications that could benefit from the emergence of liquid crystal epoxy are reviewed.
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