In past decades,the performance of supercapacitors has been greatly improved by rationalizing the electrode materials at the nanoscale.However,there is still a lack of understanding on how the charges are efficiently ...In past decades,the performance of supercapacitors has been greatly improved by rationalizing the electrode materials at the nanoscale.However,there is still a lack of understanding on how the charges are efficiently stored in the electrodes or transported across the electrolyte/electrode interface.As it is very challenging to investigate the ion-involved physical and chemical processes with single experiment or computation,combining advanced analytic techniques with electrochemical measurements,i.e.,developing in-situ characterizations,have shown considerable prospect for the better understanding of behaviors of ions in electrodes for supercapacitors.Herein,we briefly review several typical in-situ techniques and the mechanisms these techniques reveal in charge storage mechanisms specifically in supercapacitors.Possible strategies for designing better electrode materials are also discussed.展开更多
Paper-based flexible supercapacitors(SCs) show advantages due to the improved adhesion between paper and active materials, the simplified printing process and the lower cost, compared to other substrates such as plast...Paper-based flexible supercapacitors(SCs) show advantages due to the improved adhesion between paper and active materials, the simplified printing process and the lower cost, compared to other substrates such as plastics. Here we report the fabrication of solid-state yet flexible SCs by inkjetprinting a hybrid ink consisting of carbon quantum dots(CQDs) and graphene oxide(GO) platelets, followed by casting of polyvinyl alcohol(PVA)/sulfuric acid(H2SO4) gel electrolyte. The SC obtained from 100-time-printing of the hybrid ink shows a specific capacitance of ~1.0 mF cm-2 at a scan rate of 100 mV s-1, which is enhanced by nearly 150%;the whole device including paper substrate, gel electrolyte and active material demonstrates an energy density of 0.078 mW h cm-3 at a power density of 0.28 mW cm-3. In addition, the excellent mechanical strength of GO platelets ensures the good flexibility and mechanical robustness of the printed SCs, which show a retention of 98% in capacitance after being bended for 1,000 cycles at a bending radius of 7.6 mm. This study demonstrates a promising strategy for the large-scale preparation of low-cost, lightweight, and flexible/wearable energy storage devices based on carbon-based ink and paper substrate.展开更多
Direct methanol fuel cell (DMFC)has been regarded as one of promising electric generators in portable electronic equipment and electric vehicles because of the high energy conversion efficiency and low pollutant emiss...Direct methanol fuel cell (DMFC)has been regarded as one of promising electric generators in portable electronic equipment and electric vehicles because of the high energy conversion efficiency and low pollutant emissions [1,2].Electro-oxidation of methanol has been studied extensively in terms of its application in DMFC and related theoretical analysis promising anode catalyst [3-5].To date,the most for methanol oxidation is platinum (Pt).However,the development of commercial Pt-based fuel cells has been limited by the toxicity of carbon monoxide,the high cost of Pt and the aggregation of catalyst particles [6-9].Using binary or alloy catalysts is an effective strategy for the removal of CO from the catalyst surface [10-13].Extensive research reveals that ruthenium (Ru)-modified Pt nanoparticles (Pt NPs)are efficient binary electro-catalysts for methanol oxidation reaction (MOR)[14].The addition of Ru to Pt-based catalysts significantly lowers the overpotential in MOR and enhances the CO-tolerance through the ‘bifunctional mechanism'[11,12,14-18].展开更多
Lightweight yet strong paper with high toughness is desirable especially for impact protection. Herein we demonstrated electrically conductive and mechanically robust paper(AP/PB-GP) made of reduced graphene oxide via...Lightweight yet strong paper with high toughness is desirable especially for impact protection. Herein we demonstrated electrically conductive and mechanically robust paper(AP/PB-GP) made of reduced graphene oxide via interfacial crosslinking with 1-aminopyrene(AP) and 1-pyrenebutyrat(PB) small molecules. The AP/PB-GP with thickness of over ten micrometer delivers a record-high toughness(~69.67 ± 15.3 MJ m^(-3) in average), simultaneously with superior strength(close to 1 GPa), allowing an impressive specific penetration energy absorption(~0.17 MJ kg^(-1)) at high impact velocities when used for ballistic impact protection. Detailed interfacial and structural analysis reveals that the reinforcement is synergistically determined by π-π interaction and H-bonding linkage between adjacent graphene lamellae. Especially, the defective pores within the graphene platelets benefit the favorable adsorption of the pyrene-containing molecules, which imperatively maximizes the interfacial binding, facilitating deflecting crack and plastic deformation under loading. Density functional theory simulation suggests that the coupling between the polar functional groups, e.g., –COOH, at the edges of graphene platelets and –NH_(2) and –COOH of AP/PB are critical to the formation of hydrogen bonding network.展开更多
The lithium(Li)metal is one promising anode for next generation high-energy-density batteries,but the large stress fluctuation and the nonuniform Li deposition upon cycling result in a highly unstable interface of the...The lithium(Li)metal is one promising anode for next generation high-energy-density batteries,but the large stress fluctuation and the nonuniform Li deposition upon cycling result in a highly unstable interface of the Li anode.Herein,a simple yet facile engineering of the elastic interface on the Li metal anodes is designed by inserting a melamine sponge between Li and the separator.Driven by the good elasticity of the sponge,the modified Li anode maintains a Coulombic efficiency of 98.8%for 60 cycles and is cyclable at 10 mA cm^(-2) for 250 cycles,both with a high capacity of 10 mA h cm^(-2).We demonstrate that the sponge can be used to replace the conventional polypropylene as a porous yet elastic separator,showing superior cycling and rate performance as well.In addition to the efficiency of the elastic interface on the cycling stability,which is further confirmed by an in situ compression-electrochemistry measurement,the porous structure and polar groups of the sponge demonstrate an ability of regulating the transport of Li ions,leading to a uniform deposition of Li and the suppression of Li dendrites in cycling.展开更多
基金supported by the National Natural Science Foundation of China(grant Nos.51322204 and 51772282)。
文摘In past decades,the performance of supercapacitors has been greatly improved by rationalizing the electrode materials at the nanoscale.However,there is still a lack of understanding on how the charges are efficiently stored in the electrodes or transported across the electrolyte/electrode interface.As it is very challenging to investigate the ion-involved physical and chemical processes with single experiment or computation,combining advanced analytic techniques with electrochemical measurements,i.e.,developing in-situ characterizations,have shown considerable prospect for the better understanding of behaviors of ions in electrodes for supercapacitors.Herein,we briefly review several typical in-situ techniques and the mechanisms these techniques reveal in charge storage mechanisms specifically in supercapacitors.Possible strategies for designing better electrode materials are also discussed.
基金supported by the Thousand Talents Plan of Chinathe Program for New Century Excellent Talents in Universitythe National Natural Science Foundation of China (51322204 and 51772282)
文摘Paper-based flexible supercapacitors(SCs) show advantages due to the improved adhesion between paper and active materials, the simplified printing process and the lower cost, compared to other substrates such as plastics. Here we report the fabrication of solid-state yet flexible SCs by inkjetprinting a hybrid ink consisting of carbon quantum dots(CQDs) and graphene oxide(GO) platelets, followed by casting of polyvinyl alcohol(PVA)/sulfuric acid(H2SO4) gel electrolyte. The SC obtained from 100-time-printing of the hybrid ink shows a specific capacitance of ~1.0 mF cm-2 at a scan rate of 100 mV s-1, which is enhanced by nearly 150%;the whole device including paper substrate, gel electrolyte and active material demonstrates an energy density of 0.078 mW h cm-3 at a power density of 0.28 mW cm-3. In addition, the excellent mechanical strength of GO platelets ensures the good flexibility and mechanical robustness of the printed SCs, which show a retention of 98% in capacitance after being bended for 1,000 cycles at a bending radius of 7.6 mm. This study demonstrates a promising strategy for the large-scale preparation of low-cost, lightweight, and flexible/wearable energy storage devices based on carbon-based ink and paper substrate.
基金support from the National Natural Science Foundation of China (51322204 and 51772282)the National Program on Key Basic Research Project (973 Program and 2015CB932300)the Fundamental Research Funds for the Central Universities (WK2060140014 and WK2060140017)
文摘Direct methanol fuel cell (DMFC)has been regarded as one of promising electric generators in portable electronic equipment and electric vehicles because of the high energy conversion efficiency and low pollutant emissions [1,2].Electro-oxidation of methanol has been studied extensively in terms of its application in DMFC and related theoretical analysis promising anode catalyst [3-5].To date,the most for methanol oxidation is platinum (Pt).However,the development of commercial Pt-based fuel cells has been limited by the toxicity of carbon monoxide,the high cost of Pt and the aggregation of catalyst particles [6-9].Using binary or alloy catalysts is an effective strategy for the removal of CO from the catalyst surface [10-13].Extensive research reveals that ruthenium (Ru)-modified Pt nanoparticles (Pt NPs)are efficient binary electro-catalysts for methanol oxidation reaction (MOR)[14].The addition of Ru to Pt-based catalysts significantly lowers the overpotential in MOR and enhances the CO-tolerance through the ‘bifunctional mechanism'[11,12,14-18].
基金supported by the National Natural Science Foundation of China (51772282,51972299)funding from Hefei Center for Physical Science and Technology。
文摘Lightweight yet strong paper with high toughness is desirable especially for impact protection. Herein we demonstrated electrically conductive and mechanically robust paper(AP/PB-GP) made of reduced graphene oxide via interfacial crosslinking with 1-aminopyrene(AP) and 1-pyrenebutyrat(PB) small molecules. The AP/PB-GP with thickness of over ten micrometer delivers a record-high toughness(~69.67 ± 15.3 MJ m^(-3) in average), simultaneously with superior strength(close to 1 GPa), allowing an impressive specific penetration energy absorption(~0.17 MJ kg^(-1)) at high impact velocities when used for ballistic impact protection. Detailed interfacial and structural analysis reveals that the reinforcement is synergistically determined by π-π interaction and H-bonding linkage between adjacent graphene lamellae. Especially, the defective pores within the graphene platelets benefit the favorable adsorption of the pyrene-containing molecules, which imperatively maximizes the interfacial binding, facilitating deflecting crack and plastic deformation under loading. Density functional theory simulation suggests that the coupling between the polar functional groups, e.g., –COOH, at the edges of graphene platelets and –NH_(2) and –COOH of AP/PB are critical to the formation of hydrogen bonding network.
基金This work was supported by the Natural Science Foundation of China(51772282)funding from the Hefei Center for Physical Science and Technology。
文摘The lithium(Li)metal is one promising anode for next generation high-energy-density batteries,but the large stress fluctuation and the nonuniform Li deposition upon cycling result in a highly unstable interface of the Li anode.Herein,a simple yet facile engineering of the elastic interface on the Li metal anodes is designed by inserting a melamine sponge between Li and the separator.Driven by the good elasticity of the sponge,the modified Li anode maintains a Coulombic efficiency of 98.8%for 60 cycles and is cyclable at 10 mA cm^(-2) for 250 cycles,both with a high capacity of 10 mA h cm^(-2).We demonstrate that the sponge can be used to replace the conventional polypropylene as a porous yet elastic separator,showing superior cycling and rate performance as well.In addition to the efficiency of the elastic interface on the cycling stability,which is further confirmed by an in situ compression-electrochemistry measurement,the porous structure and polar groups of the sponge demonstrate an ability of regulating the transport of Li ions,leading to a uniform deposition of Li and the suppression of Li dendrites in cycling.
