In the last decade, pyrolyzed-carbon-based composites have attracted much attention for their applications in micro-supercapacitors. Although various methods have been investigated to improve the performance of pyroly...In the last decade, pyrolyzed-carbon-based composites have attracted much attention for their applications in micro-supercapacitors. Although various methods have been investigated to improve the performance of pyrolyzed carbons, such as conductivity, energy storage density and cycling performance, effective methods for the integration and mass-production of pyrolyzed-carbon- based composites on a large scale are lacking. Here, we report the development of an optimized photolithographic technique for the fine micropatterning of photoresist/chitosan-coated carbon nanotube （CHIT-CNT） composite. After subsequent pyrolysis, the fabricated carbon/CHIT-CNT microelectrode-based micro-supercapacitor has a high capacitance （6.09 mF.cm-2） and energy density （4.5 mWh.cm-3） at a scan rate of 10 mV.s-L Additionally, the micro-supercapacitor has a remarkable long-term cyclability, with 99.9% capacitance retention after 10,000 cyclic voltammetry cycles. This design and microfabrication process allow the application of carbon microelectromechanical system （C-MEMS）-based micro-supercapacitors due to their high potential for enhancing the mechanical and electrochemical performance of micro-supercapacitors.展开更多
Planar micro-supercapacitors （MSCs） have drawn extensive research attention owing to their unique structural design and size compatibility for microelectronic devices. Graphene has been widely used to improve the pe...Planar micro-supercapacitors （MSCs） have drawn extensive research attention owing to their unique structural design and size compatibility for microelectronic devices. Graphene has been widely used to improve the performance of microscale electrochemical capacitors. However, investigations of an intrinsic electrochemical mechanism for graphene-based microscale devices are still not sufficient. Here, micro-supercapacitors with various typical architectures are fabricated as models to study the graphene effect, and their electrochemical performance is also evaluated. The results show that ionic accessibility and adsorption are greatly improved after the introduction of the holey graphene intermediate layer. This study provides a new route to understand intrinsic electrochemical behaviors and possesses exciting potential for highly efficient on-chip micro-energy storage.展开更多
Planar micro-supercapacitors show great potential as the energy storage unit in miniaturized electronic devices. Asymmetric structures have been widely inves- tigated in micro-supercapacitors, and carbon-based materia...Planar micro-supercapacitors show great potential as the energy storage unit in miniaturized electronic devices. Asymmetric structures have been widely inves- tigated in micro-supercapacitors, and carbon-based materials are commonly applied in the electrodes. To integrate different metal oxides in both electrodes in micro-supercapacitors, the critical challenge is the pairing of different faradic metal oxides. Herein, we propose a strategy of matching the voltage and capadtance of two faradic materials that are fully integrated into one high-performance asymmetric micro-supercapacitor by a facile and controllable fabrication process. The fabricated micro-supercapacitors employ MnO2 as the positive active material and Fe203 as the negative active material, respectively. The planar asymmetric micro-supercapacitors possess a high capacitance of 60 F-cm-3, a high energy density of 12 mW.h.cm-3, and a broad operation voltage range up to 1.2 V.展开更多
As one of the most important micro energy storage devices(MESDs),graphene-based micro-supercapacitors(G-MSCs)possess the advantages of excellent flexibility,long cycle life,affordability and high reliability.In most c...As one of the most important micro energy storage devices(MESDs),graphene-based micro-supercapacitors(G-MSCs)possess the advantages of excellent flexibility,long cycle life,affordability and high reliability.In most cases,constructing three-dimensional(3D)graphene networks is widely utilized to promote the permeation of electrolyte and enhance the utilization of active materials.In this work,conventional freeze-drying process is utilized in the fabrication of G-MSCs to constitute 3D interconnected networks micro-electrodes,and further by regulating the composition of inks,carbon spheres(CSs)at different mass loadings are introduced into the graphene scaffolds to further increase the active sites of the micro-electrodes.The fabricated all carbon-based MSC with the optimal mass loading of CSs(0.406 mg cm^(-2))exhibits a high specific areal capacitance of 17.01mF cm^(-2)at the scan rate of 10mV s^(-1)and a capacitance retention of 93.14%after 10000 cycles at the scan rate of 500 mV s^(-1).The proposed microfabrication process is facile and fully compatible with modern microtechnologies and will be highly suitable for large-scale production and integration.展开更多
Hybrid or composite heterostructured electrode materials have been widely studied for their potential application in electrochemical energy storage. Whereas their physical or chemical properties could be affected sign...Hybrid or composite heterostructured electrode materials have been widely studied for their potential application in electrochemical energy storage. Whereas their physical or chemical properties could be affected significantly by modulating the heterogeneous interface, the underlying mechanisms are not yet fully understood. In this work, we fabricated an electrochemical energy storage device with a MoS2 nanosheet/MnO2 nanowire heterostructure and designed two charge/discharge channels to study the effect of the heterogeneous interface on the energy storage performances. Electrochemical measurements show that a capadty improvement of over 50% is achieved when the metal current collector was in contact with the MnO2 instead of the MoS2 side. We propose that this enhancement is due to the unidirectional conductivity of the MoS2/MnO2 heterogeneous interface, resulting from the unimpeded electrical transport in the MnO2-MoS2 channel along with the blocking effect on the electron transport in the MoS2-MnO2 channel, which leads to reaction kinetics optimization. The present study thus provides important insights that will improve our understanding of heterostructured electrode materials for electrochemical energy storage.展开更多
Surface modification of graphene oxide(GO)is a powerful strategy to develop its energy density for electrochemical energy storage.However,pre-modified GO always exhibits unsatisfactory hydrophilia and its ink-relevant...Surface modification of graphene oxide(GO)is a powerful strategy to develop its energy density for electrochemical energy storage.However,pre-modified GO always exhibits unsatisfactory hydrophilia and its ink-relevant utilization is extremely limited.Although GO ink is widely utilized in fabricating micro energy storage devices via extrusion-based 3D-printing,simultaneously obtaining satisfactory hydrophilia and high energy density still remains a challenge.In this work,an in-situ surface engineering strategy was employed to enhance the performance of GO micro-supercapacitor chips.Three dimensionally printed GO micro-supercapacitor chips were treated with pyrrole monomer to achieve selective and spontaneous anchoring of polypyrrole on the microelectrodes without affecting interspaces between the finger electrodes.The interface-reinforced graphene scaffolds were edge-welded and exhibited a considerably improved specific capacitance,from 13.6 to 128.4 mF·cm^(-2).These results are expected to provide a new method for improving the performance of micro-supercapacitors derived from GO inks and further strengthen the practicability of 3D printing techniques in fabricating energy storage devices.展开更多
In this study, expanded graphite and natural graphite were introduced into resin-based friction materials, and the tribological behavior of the composites was investigated. The tribo-performance of the two friction co...In this study, expanded graphite and natural graphite were introduced into resin-based friction materials, and the tribological behavior of the composites was investigated. The tribo-performance of the two friction composites was evaluated using a constant speed friction tester. The results showed that the expanded graphite composite (EGC) displayed better lubricity in both the fading and the recovery processes. The wear rate of the EGC decreased by 22.43%more than that of the natural graphite composite (NGC). In the fading process, and the EGC enhanced the stability of the coefficient of friction. The recovery maintenance rate of the NGC was 4.66% higher than that of the EGC. It can be concluded that expanded graphite plays an important role in the formation of a stable contact plateau and can effectively reduce the wear.展开更多
基金This work was supported by the National Basic Research Program of China （No. 2013CB934103）, the National Natural Science Fund for Distinguished Young Scholars （No. 51425204）, the National Natural Science Foundation of China （Nos. 51521001 and 51502227）, the China Postdoctoral Science Foundation （No. 2015T80845）, and the Fundamental Research Funds for the Central Universities （WUT： Nos. 2014- IV-062, 2014-IV-147, 2014-YB-002, and 2016III005）.
文摘In the last decade, pyrolyzed-carbon-based composites have attracted much attention for their applications in micro-supercapacitors. Although various methods have been investigated to improve the performance of pyrolyzed carbons, such as conductivity, energy storage density and cycling performance, effective methods for the integration and mass-production of pyrolyzed-carbon- based composites on a large scale are lacking. Here, we report the development of an optimized photolithographic technique for the fine micropatterning of photoresist/chitosan-coated carbon nanotube （CHIT-CNT） composite. After subsequent pyrolysis, the fabricated carbon/CHIT-CNT microelectrode-based micro-supercapacitor has a high capacitance （6.09 mF.cm-2） and energy density （4.5 mWh.cm-3） at a scan rate of 10 mV.s-L Additionally, the micro-supercapacitor has a remarkable long-term cyclability, with 99.9% capacitance retention after 10,000 cyclic voltammetry cycles. This design and microfabrication process allow the application of carbon microelectromechanical system （C-MEMS）-based micro-supercapacitors due to their high potential for enhancing the mechanical and electrochemical performance of micro-supercapacitors.
基金This work was supported by the National Basic Research Program of China （Nos. 2013CB934103 and 2012CB933003）, the International Science ＆ Technology Cooperation Program of China （No. 2013DFA50840）, the National Natural Science Foundation of China （Nos. 51522001 and 51272197）, the National Science Fund for Hubei Provincial Natural Science Young Scholars （No. 51425204）, the Hubei Science Fund for Distinguished Young Scholars （No. 2014CFA035）, the Fundamental Research Funds for the Central Universities （WUT： 2015-PY-2, 2015-CL-A1-03）. We are deeply thankful to Prof. Charles M. Lieber of Harvard University, Prof. Dongyuan Zhao of Fudan University, and Prof. Jun Liu of Pacific Northwest National Laboratory for their stimulating discussion and kind help.
文摘Planar micro-supercapacitors （MSCs） have drawn extensive research attention owing to their unique structural design and size compatibility for microelectronic devices. Graphene has been widely used to improve the performance of microscale electrochemical capacitors. However, investigations of an intrinsic electrochemical mechanism for graphene-based microscale devices are still not sufficient. Here, micro-supercapacitors with various typical architectures are fabricated as models to study the graphene effect, and their electrochemical performance is also evaluated. The results show that ionic accessibility and adsorption are greatly improved after the introduction of the holey graphene intermediate layer. This study provides a new route to understand intrinsic electrochemical behaviors and possesses exciting potential for highly efficient on-chip micro-energy storage.
基金This work was supported by the National Key Research and Development Program of China （No. 2016YFA0202603）, the National Basic Research Program of China （No. 2013CB934103）, the Programme of Introducing Talents of Discipline to Universities （No. B17034）, the National Natural Science Foundation of China （Nos. 51521001, 51502227, 51579198, and 51302203）, the National Natural Science Fund for Distinguished Young Scholars （No. 51425204）, and the Fundamental Research Funds for the Central Universities （WUT： 2016III001, 2016III005, 2016III006）.
文摘Planar micro-supercapacitors show great potential as the energy storage unit in miniaturized electronic devices. Asymmetric structures have been widely inves- tigated in micro-supercapacitors, and carbon-based materials are commonly applied in the electrodes. To integrate different metal oxides in both electrodes in micro-supercapacitors, the critical challenge is the pairing of different faradic metal oxides. Herein, we propose a strategy of matching the voltage and capadtance of two faradic materials that are fully integrated into one high-performance asymmetric micro-supercapacitor by a facile and controllable fabrication process. The fabricated micro-supercapacitors employ MnO2 as the positive active material and Fe203 as the negative active material, respectively. The planar asymmetric micro-supercapacitors possess a high capacitance of 60 F-cm-3, a high energy density of 12 mW.h.cm-3, and a broad operation voltage range up to 1.2 V.
基金This work was supported by the National Natural Science Fund for Distinguished Young Scholars(51425204)the National Natural Science Foundation of China(51521001,51502227,51579198,51802239)+6 种基金the National Key Research and Development Program of China(2016YFA0202603,2016YFA0202604)the Programme of Introducing Talents of Discipline to Universities(B17034)the China Postdoctoral Science Foundation(2015T80845)the Yellow Crane Talent(Science&Technology)Program of Wuhan Citythe Wuhan Morning Light Plan of Youth Science and Technology(No.2017050304010316)the Fundamental Research Funds for the Central Universities(WUT:2017III005,2017III009,2018IVA091)the Students innovation and entrepreneurship training program(WUT:20171049701005).
文摘As one of the most important micro energy storage devices(MESDs),graphene-based micro-supercapacitors(G-MSCs)possess the advantages of excellent flexibility,long cycle life,affordability and high reliability.In most cases,constructing three-dimensional(3D)graphene networks is widely utilized to promote the permeation of electrolyte and enhance the utilization of active materials.In this work,conventional freeze-drying process is utilized in the fabrication of G-MSCs to constitute 3D interconnected networks micro-electrodes,and further by regulating the composition of inks,carbon spheres(CSs)at different mass loadings are introduced into the graphene scaffolds to further increase the active sites of the micro-electrodes.The fabricated all carbon-based MSC with the optimal mass loading of CSs(0.406 mg cm^(-2))exhibits a high specific areal capacitance of 17.01mF cm^(-2)at the scan rate of 10mV s^(-1)and a capacitance retention of 93.14%after 10000 cycles at the scan rate of 500 mV s^(-1).The proposed microfabrication process is facile and fully compatible with modern microtechnologies and will be highly suitable for large-scale production and integration.
基金This work was supported by the National Key Research and Development Program of China （No. 2016YFA0202603）, the National Basic Research Program of China （No. 2013CB934103）, the Programme of Introducing Talents of Discipline to Universities （No. B17034）, the National Natural Science Foundation of China （No. 51521001）, the National Natural Science Fund for Distinguished Young Scholars （No. 51425204）, and the Fundamental Research Funds for the Central Universities （WUT： 2016III001, 2017III009）, Prof. Liqiang Mai gratefully acknowledged financial support from China Scholarship Council （No. 201606955096）.
文摘Hybrid or composite heterostructured electrode materials have been widely studied for their potential application in electrochemical energy storage. Whereas their physical or chemical properties could be affected significantly by modulating the heterogeneous interface, the underlying mechanisms are not yet fully understood. In this work, we fabricated an electrochemical energy storage device with a MoS2 nanosheet/MnO2 nanowire heterostructure and designed two charge/discharge channels to study the effect of the heterogeneous interface on the energy storage performances. Electrochemical measurements show that a capadty improvement of over 50% is achieved when the metal current collector was in contact with the MnO2 instead of the MoS2 side. We propose that this enhancement is due to the unidirectional conductivity of the MoS2/MnO2 heterogeneous interface, resulting from the unimpeded electrical transport in the MnO2-MoS2 channel along with the blocking effect on the electron transport in the MoS2-MnO2 channel, which leads to reaction kinetics optimization. The present study thus provides important insights that will improve our understanding of heterostructured electrode materials for electrochemical energy storage.
基金supported by the National Key Research and Development Program of China(No.2020YFA715000)the National Natural Science Foundation of China(No.51802239)+3 种基金the National Key Research and Development Program of China(No.2019YFA0704902)Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(Nos.XHT2020-005 and XHT2020-003)the Natural Science Foundation of Hubei Province(No.2019CFA001)the Fundamental Research Funds for the Central Universities(Nos.2020III011GX,2020IVB057,2019IVB054,2019III062JL,and 2019-YB-008).
文摘Surface modification of graphene oxide(GO)is a powerful strategy to develop its energy density for electrochemical energy storage.However,pre-modified GO always exhibits unsatisfactory hydrophilia and its ink-relevant utilization is extremely limited.Although GO ink is widely utilized in fabricating micro energy storage devices via extrusion-based 3D-printing,simultaneously obtaining satisfactory hydrophilia and high energy density still remains a challenge.In this work,an in-situ surface engineering strategy was employed to enhance the performance of GO micro-supercapacitor chips.Three dimensionally printed GO micro-supercapacitor chips were treated with pyrrole monomer to achieve selective and spontaneous anchoring of polypyrrole on the microelectrodes without affecting interspaces between the finger electrodes.The interface-reinforced graphene scaffolds were edge-welded and exhibited a considerably improved specific capacitance,from 13.6 to 128.4 mF·cm^(-2).These results are expected to provide a new method for improving the performance of micro-supercapacitors derived from GO inks and further strengthen the practicability of 3D printing techniques in fabricating energy storage devices.
基金This work was financially supported by the National Key Research Program of China(2016YFA0201001)Major scientific and technological innovation in Hubei(2017AAA112 and 2018AAA015)+1 种基金the Open research project of the Ministry of Education's Engineering Research Center of Nano-Geo Materials(NGM2017KFO11)the laboratory open foundation of the 2016-2017 academic year(SKJ2018052).
文摘In this study, expanded graphite and natural graphite were introduced into resin-based friction materials, and the tribological behavior of the composites was investigated. The tribo-performance of the two friction composites was evaluated using a constant speed friction tester. The results showed that the expanded graphite composite (EGC) displayed better lubricity in both the fading and the recovery processes. The wear rate of the EGC decreased by 22.43%more than that of the natural graphite composite (NGC). In the fading process, and the EGC enhanced the stability of the coefficient of friction. The recovery maintenance rate of the NGC was 4.66% higher than that of the EGC. It can be concluded that expanded graphite plays an important role in the formation of a stable contact plateau and can effectively reduce the wear.
