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 unde...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.展开更多
Crosslinking thermosets with hyperbranched polymers confers them superior comprehensive performance.However,it still remains a further understanding of polymer crosslinking from the molecular chains to the role of agg...Crosslinking thermosets with hyperbranched polymers confers them superior comprehensive performance.However,it still remains a further understanding of polymer crosslinking from the molecular chains to the role of aggregates.In this study,three hyperbranched polysiloxane structures(HBPSi-R)are synthesized as model macromolecules,each featuring distinct terminal groups(R denotes amino,epoxy,and vinyl groups)while similar molecular backbone(Si-O-C).These structures were subsequently copolymerized with epoxy monomers to construct interpenetrating HBPSi-R/epoxy/anhydride co-polymer systems.The spatial molecular configuration and flexible Si-O-C branches of HBPSi-R endow them with remarkable reinforcement and toughening effects.Notably,an optimum impact strength of 28.9 kJ mol^(−1) is achieved with a mere 3%loading of HBPSi-V,nearly three times that of the native epoxy(12.9 kJ mol^(−1)).By contrasting the terminal effects,the aggregation states and crosslinking modes were proposed,thus clarifying the supramolecular-dominant aggregation mechanism and covalent-dominant dispersion mechanism,which influences the resulting material properties.This work underscores the significance of aggregate science in comprehending polymer crosslinking and provides theoretical insights for tailoring material properties at a refined molecular level in the field of polymer science.展开更多
基金the financial support of this work by the Science,Technology,and Innovation Commission of Shenzhen Municipality(Program No.JCYJ20180508151856806,No.JCYJ20180306171355233)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(Program No.CX201944)。
文摘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.
基金National Natural Science Foundation of China,Grant/Award Number:22175143Key Research and Development Project of Shaanxi,Grant/Award Number:2022GY-353+1 种基金Science Center for Gas Turbine Project,Grant/Award Number:P2022-DB-V-001-001Fundamental Research Funds for the Central Universities,Grant/Award Number:D5000230086。
文摘Crosslinking thermosets with hyperbranched polymers confers them superior comprehensive performance.However,it still remains a further understanding of polymer crosslinking from the molecular chains to the role of aggregates.In this study,three hyperbranched polysiloxane structures(HBPSi-R)are synthesized as model macromolecules,each featuring distinct terminal groups(R denotes amino,epoxy,and vinyl groups)while similar molecular backbone(Si-O-C).These structures were subsequently copolymerized with epoxy monomers to construct interpenetrating HBPSi-R/epoxy/anhydride co-polymer systems.The spatial molecular configuration and flexible Si-O-C branches of HBPSi-R endow them with remarkable reinforcement and toughening effects.Notably,an optimum impact strength of 28.9 kJ mol^(−1) is achieved with a mere 3%loading of HBPSi-V,nearly three times that of the native epoxy(12.9 kJ mol^(−1)).By contrasting the terminal effects,the aggregation states and crosslinking modes were proposed,thus clarifying the supramolecular-dominant aggregation mechanism and covalent-dominant dispersion mechanism,which influences the resulting material properties.This work underscores the significance of aggregate science in comprehending polymer crosslinking and provides theoretical insights for tailoring material properties at a refined molecular level in the field of polymer science.