Chemically exfoliated nanosheets have exhibited great potential for applications in various electronic devices.Solution-based processing strategies such as inkjet printing provide a low-cost,environmentally friendly,a...Chemically exfoliated nanosheets have exhibited great potential for applications in various electronic devices.Solution-based processing strategies such as inkjet printing provide a low-cost,environmentally friendly,and scalable route for the fabrication of flexible devices based on functional inks of twodimensional nanosheets.In this study,chemically exfoliated high-k perovskite nanosheets(i.e.,Ca_(2)Nb_(3)O_(10)and Ca_(2)NaNb_(4)O_(13))are well dispersed in appropriate solvents to prepare printable inks,and then,a series of microcapacitors with Ag and graphene electrodes are printed.The resulting microcapacitors,Ag/Ca_(2)Nb_(3)O_(10)/Ag,graphene/Ca_(2)Nb_(3)O_(10)/graphene,and graphene/Ca_(2)NaNb_(4)O_(13)/graphene,demonstrate high capacitance densities of 20,80,and 150 nF/cm^(2) and high dielectric constants of 26,110.and 200,respectively.Such dielectric enhancement in the microcapacitors with graphene electrodes is possibly attributed to the dielectric/graphene interface.In addition,these microcapacitors also exhibit good insulating performance with a moderate electrical breakdown strength of approximately 1 MV/cm,excellent flexibility,and thermal stability up to 200℃.This work demonstrates the potential of high-k perovskite nanosheets for additive manufacturing of flexible high-performance dielectric capacitors.展开更多
Two-dimensional transition-metal carbides(MXenes)have superhydrophilic surfaces and superior metal conductivity,making them competitive in the field of electrochemical energy storage.However,MXenes with layered struct...Two-dimensional transition-metal carbides(MXenes)have superhydrophilic surfaces and superior metal conductivity,making them competitive in the field of electrochemical energy storage.However,MXenes with layered structures are easily stackable,which reduces the ion accessibility and transport paths,thus limiting their electrochemical performance.To fully exploit the advantages of MXenes in electrochemical energy storage,this study reports the etching of large-sized MXene into nanosheets with nanoscale ion channels via a chemical oxidation method.While the resulting ion-channel MXene electrodes retain the excellent mechanical strength and electrical conductivity of large-sized MXene nanosheets,they can effectively shorten the ion transport distance and improve the overall electrochemical activity.The fabricated self-healing MXene-based zinc-ion microcapacitor exhibits a high areal specific capacitance(532.8 mF cm^(-2))at the current density of 2mA cm^(-2),a low self-discharge rate(4.4 mV h^(-1)),and high energy density of 145.1μWh cm^(-2)at the power density of 2800μW cm^(-2).The proposed nanoscale ion channel structure provides an alternative strategy for constructing high-performance electrochemical energy storage electrodes,and has great application prospects in the fields of electrochemical energy storage and flexible electronics.展开更多
基金supported by the Basic Science Center Program of National Natural Science Foundation of China(51788104)the National Natural Science Foundation of China(52172124 and51872214)the Fundamental Research Funds for the Central Universities(WUT:2021III019JC,2018III041GX)。
文摘Chemically exfoliated nanosheets have exhibited great potential for applications in various electronic devices.Solution-based processing strategies such as inkjet printing provide a low-cost,environmentally friendly,and scalable route for the fabrication of flexible devices based on functional inks of twodimensional nanosheets.In this study,chemically exfoliated high-k perovskite nanosheets(i.e.,Ca_(2)Nb_(3)O_(10)and Ca_(2)NaNb_(4)O_(13))are well dispersed in appropriate solvents to prepare printable inks,and then,a series of microcapacitors with Ag and graphene electrodes are printed.The resulting microcapacitors,Ag/Ca_(2)Nb_(3)O_(10)/Ag,graphene/Ca_(2)Nb_(3)O_(10)/graphene,and graphene/Ca_(2)NaNb_(4)O_(13)/graphene,demonstrate high capacitance densities of 20,80,and 150 nF/cm^(2) and high dielectric constants of 26,110.and 200,respectively.Such dielectric enhancement in the microcapacitors with graphene electrodes is possibly attributed to the dielectric/graphene interface.In addition,these microcapacitors also exhibit good insulating performance with a moderate electrical breakdown strength of approximately 1 MV/cm,excellent flexibility,and thermal stability up to 200℃.This work demonstrates the potential of high-k perovskite nanosheets for additive manufacturing of flexible high-performance dielectric capacitors.
基金supported by the National Natural Science Foundation of China(51871104,12204010,and 52272177)the Fundamental Research Funds for the Central Universities(2019kfy RCPY074)the Natural Science Foundation of Anhui Province(2008085QA27,2008085QA41)。
文摘Two-dimensional transition-metal carbides(MXenes)have superhydrophilic surfaces and superior metal conductivity,making them competitive in the field of electrochemical energy storage.However,MXenes with layered structures are easily stackable,which reduces the ion accessibility and transport paths,thus limiting their electrochemical performance.To fully exploit the advantages of MXenes in electrochemical energy storage,this study reports the etching of large-sized MXene into nanosheets with nanoscale ion channels via a chemical oxidation method.While the resulting ion-channel MXene electrodes retain the excellent mechanical strength and electrical conductivity of large-sized MXene nanosheets,they can effectively shorten the ion transport distance and improve the overall electrochemical activity.The fabricated self-healing MXene-based zinc-ion microcapacitor exhibits a high areal specific capacitance(532.8 mF cm^(-2))at the current density of 2mA cm^(-2),a low self-discharge rate(4.4 mV h^(-1)),and high energy density of 145.1μWh cm^(-2)at the power density of 2800μW cm^(-2).The proposed nanoscale ion channel structure provides an alternative strategy for constructing high-performance electrochemical energy storage electrodes,and has great application prospects in the fields of electrochemical energy storage and flexible electronics.
