As a promising energy-storage device,the hybrid lithium-ion capacitor coupling with both a large energy density battery-type anode and a high power density capacitor-type cathode is attracting great attention.For the ...As a promising energy-storage device,the hybrid lithium-ion capacitor coupling with both a large energy density battery-type anode and a high power density capacitor-type cathode is attracting great attention.For the sake of improving the energy density of hybrid lithium-ion capacitor,the free-standing anodes with good electrochemical performance are essential.Herein,we design an effective electrospinning strategy to prepare free-standing MnS/Co4S3/Ni3S2/Ni/C-nanofibers(TMSs/Ni/C-NFs)film and firstly use it as a binder-free anode for hybrid lithium-ion capacitor.We find that the carbon nanofibers can availably prevent MnS/Co4S3/Ni3S2/Ni nanoparticles from aggregation as well as significantly improve the electrochemical performance.Therefore,the binder-free TMSs/Ni/C-NFs membrane displays an ultrahigh reversible capacity of 1246.9 m Ah g-1at 100 m A g-1,excellent rate capability(398 mAh g-1 at2000 mA g-1),and long-term cyclic endurance.Besides,we further assemble the hybrid lithium-ion capacitor,which exhibits a high energy density of 182.0 Wh kg-1at 121.1 W kg-1(19.0 Wh kg-1 at 3512.5 W kg-1)and remarkable cycle life.展开更多
Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for comm...Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries.Here,3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated(referred to as PEMAC@NDCN)by a facile self-templated approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability,which outperforms those of commercial Pt/C and RuO_(2).Theoretical calculations and control experi-ments reveal the boosted electron transfer,electrolyte mass/ion transports,and abundant active surface site preferences.Moreover,the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density,capacity,and discharge-charge cycling stability(over 2160 cycles)compared to the reference Pt/C+RuO_(2).Solid-state Zn-air batteries enable a high power density of 211 mW cm^(−2),energy density of 1056 Wh kg^(−1),stable charge-discharge cycling of 2580 cycles for 50 mA cm^(−2),and wide temperature tolerance from−40 to 70℃with retention of 86%capacity compared to room-temperature counterparts,illustrating prospects over harsh operations.展开更多
The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur c...The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur cathodes,which have rarely been realized due to massive passivation and shuttling.Herein,microspheres of a carbon-carbon nitride composite(C@CN)with large mesopores are fabricated via molecular cooperative assembly.Using the C@CN-based electrodes,the effects of the large mesopores and N-functional groups on the electrochemical behavior of sulfur in LSB cells are thoroughly investigated under ultrahigh sulfur-loading conditions(>15 mgS cm^(-2)).Furthermore,for high-energy-density LSBs,the C@CN powders are pelletized into a thick free-standing electrode(thickness:500^m;diameter:11 mm)via a simple briquette process;here,the total amount of energy stored by the LSB cells is 39 mWh,corresponding to a volumetric energy density of 440 Wh L-1 with an areal capacity of 24.9 and 17.5 mAh cm^(-2) at 0.47 and 4.7 mA cm^(-2),respectively(at 24mgS cm^(-2)).These results have significantly surpassed most recent records due to the synergy among the large mesopores,(poly)sulfide-philic surfaces,and thick electrodes.The developed strategy with its potential for scale-up successfully fills the gap between laboratory-scale cells and practical cells without sacrificing the high areal capacity and high energy density,providing a solid foundation for the development of practical LSBs.展开更多
Background: The use of standing desks has been associated with greater metabolic cost as compared to traditional seated desks. However, it is unclear as to the metabolic impact of standing desks in normal weight versu...Background: The use of standing desks has been associated with greater metabolic cost as compared to traditional seated desks. However, it is unclear as to the metabolic impact of standing desks in normal weight versus obese men and women. Methods: We compared the metabolic cost of using a standing and seated desk in 14 obese and 19 normal weight men and women. Subjects reported to the lab on a single occasion and participated in two, 30-minute sessions of standing and seated desk work (i.e., typing), in random order. Expired gases were collected during the 2-hour period and calorie expenditure was estimated using indirect calorimetry. Results: We noted a significant (p = 0.013) increase in energy expenditure of 7.4 kcal•30 minutes−1 (+14.7%) during standing as compared to seated for the obese group. No significant difference in energy expenditure was noted for the normal weight group (p = 0.674). A condition effect was noted for heart rate and diastolic blood pressure, with standing being significantly higher than seated for both variables (p 0.05). Conclusion: The use of a standing desk modestly increases energy expenditure in obese subjects but does not have the same effect in those of normal weight. It is unknown whether the increased energy expenditure would be maintained over time in the obese subjects/individuals, as they may adapt to the standing position. Moreover, if normal weight individuals choose a standing desk, they should do so for reasons unrelated to increased energy expenditure (e.g., improved spine health, greater feeling of productivity).展开更多
The role of Photovoltaic technologies integrated or attached to the building envelope is crucial in managing the building energy demand.In this paper,the performance of PV technologies with the mounting methods of Bui...The role of Photovoltaic technologies integrated or attached to the building envelope is crucial in managing the building energy demand.In this paper,the performance of PV technologies with the mounting methods of Build-ing integrated and Free-standing(Building attached)is discussed for six different climate zone of the country.A PVGIS program proposed with three PV cell technologies(Crystalline Silicon,Copper indium diselenide,Cad-mium Telluride)is used to evaluate monthly energy generation potential and losses of the 2 kW p grid-connected PV system at the latitude and 90°.A 2 kW p PV system is chosen for Economic Weaker Section(EWS)housing schemes depending upon the roof area.From the evaluation,the performance parameter has been estimated.A new parameter Energy Deviation(ED),is proposed to choose the best PV technology in terms of performance.The results of ED agree with the parameters Performance Ratio(PR)and Capacity Factor(CF)defined under the IEC Standard 61724.The potential generation of PV technologies at 90°varies from 41%(Warm and Humid)to 64%(Cold and Sunny)when compared with the latitude.In case of Cold and Sunny and Cold and Cloudy at 90°,the generation performance of Copper indium diselenide is found better in Building integrated and Free-standing mounting methods,respectively.For the remaining zones,Cadmium Telluride technology shows better results.The Percentage loss in the system is found to be minimum in the case of Cold and Sunny,varies between 17%and 25%,and maximum is found for Warm and Humid and varies between 23.2%and 33.4%for the proposed PV technologies.The grid feed-in energy from these EWS houses for all the technologies and climatic zones is found above 45%.It is seen that the combined energy generation from the envelopes(Roof,walls,and facades)makes the houses energy plus in nature.The study has important implications for the government to promote the building integrated Photovoltaic policies in the country.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51072173, 51272221 and 51302239)Specialized Research Fund for the Doctoral Program of Higher Education (Grant Nos. 20134301130001)the Natural Science Foundation of Hunan Province, China (Grant Nos. 13JJ4051).
文摘As a promising energy-storage device,the hybrid lithium-ion capacitor coupling with both a large energy density battery-type anode and a high power density capacitor-type cathode is attracting great attention.For the sake of improving the energy density of hybrid lithium-ion capacitor,the free-standing anodes with good electrochemical performance are essential.Herein,we design an effective electrospinning strategy to prepare free-standing MnS/Co4S3/Ni3S2/Ni/C-nanofibers(TMSs/Ni/C-NFs)film and firstly use it as a binder-free anode for hybrid lithium-ion capacitor.We find that the carbon nanofibers can availably prevent MnS/Co4S3/Ni3S2/Ni nanoparticles from aggregation as well as significantly improve the electrochemical performance.Therefore,the binder-free TMSs/Ni/C-NFs membrane displays an ultrahigh reversible capacity of 1246.9 m Ah g-1at 100 m A g-1,excellent rate capability(398 mAh g-1 at2000 mA g-1),and long-term cyclic endurance.Besides,we further assemble the hybrid lithium-ion capacitor,which exhibits a high energy density of 182.0 Wh kg-1at 121.1 W kg-1(19.0 Wh kg-1 at 3512.5 W kg-1)and remarkable cycle life.
基金supported by the Creative Materials Discovery Program (Grant No. 2018M3D1A1057844) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICTthe Basic Science Research Program through the NRF funded by the Ministry of Science, ICT and Future Planning (Grant No. 2021R1A2B5B01002879).
文摘Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries.Here,3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated(referred to as PEMAC@NDCN)by a facile self-templated approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability,which outperforms those of commercial Pt/C and RuO_(2).Theoretical calculations and control experi-ments reveal the boosted electron transfer,electrolyte mass/ion transports,and abundant active surface site preferences.Moreover,the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density,capacity,and discharge-charge cycling stability(over 2160 cycles)compared to the reference Pt/C+RuO_(2).Solid-state Zn-air batteries enable a high power density of 211 mW cm^(−2),energy density of 1056 Wh kg^(−1),stable charge-discharge cycling of 2580 cycles for 50 mA cm^(−2),and wide temperature tolerance from−40 to 70℃with retention of 86%capacity compared to room-temperature counterparts,illustrating prospects over harsh operations.
基金the R&D Convergence Program of NST(National Research Council of Science&Technology)of the Republic of Korea(CAP-15-02-KBSI)a National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(No.2019R1C1C1007745)a National Research Foundation of Korea(NRF)grant funded by the Korean Government(Ministry of Science,ICT&Future Planning)(No.2019R1A4A2001527).
文摘The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur cathodes,which have rarely been realized due to massive passivation and shuttling.Herein,microspheres of a carbon-carbon nitride composite(C@CN)with large mesopores are fabricated via molecular cooperative assembly.Using the C@CN-based electrodes,the effects of the large mesopores and N-functional groups on the electrochemical behavior of sulfur in LSB cells are thoroughly investigated under ultrahigh sulfur-loading conditions(>15 mgS cm^(-2)).Furthermore,for high-energy-density LSBs,the C@CN powders are pelletized into a thick free-standing electrode(thickness:500^m;diameter:11 mm)via a simple briquette process;here,the total amount of energy stored by the LSB cells is 39 mWh,corresponding to a volumetric energy density of 440 Wh L-1 with an areal capacity of 24.9 and 17.5 mAh cm^(-2) at 0.47 and 4.7 mA cm^(-2),respectively(at 24mgS cm^(-2)).These results have significantly surpassed most recent records due to the synergy among the large mesopores,(poly)sulfide-philic surfaces,and thick electrodes.The developed strategy with its potential for scale-up successfully fills the gap between laboratory-scale cells and practical cells without sacrificing the high areal capacity and high energy density,providing a solid foundation for the development of practical LSBs.
文摘Background: The use of standing desks has been associated with greater metabolic cost as compared to traditional seated desks. However, it is unclear as to the metabolic impact of standing desks in normal weight versus obese men and women. Methods: We compared the metabolic cost of using a standing and seated desk in 14 obese and 19 normal weight men and women. Subjects reported to the lab on a single occasion and participated in two, 30-minute sessions of standing and seated desk work (i.e., typing), in random order. Expired gases were collected during the 2-hour period and calorie expenditure was estimated using indirect calorimetry. Results: We noted a significant (p = 0.013) increase in energy expenditure of 7.4 kcal•30 minutes−1 (+14.7%) during standing as compared to seated for the obese group. No significant difference in energy expenditure was noted for the normal weight group (p = 0.674). A condition effect was noted for heart rate and diastolic blood pressure, with standing being significantly higher than seated for both variables (p 0.05). Conclusion: The use of a standing desk modestly increases energy expenditure in obese subjects but does not have the same effect in those of normal weight. It is unknown whether the increased energy expenditure would be maintained over time in the obese subjects/individuals, as they may adapt to the standing position. Moreover, if normal weight individuals choose a standing desk, they should do so for reasons unrelated to increased energy expenditure (e.g., improved spine health, greater feeling of productivity).
文摘The role of Photovoltaic technologies integrated or attached to the building envelope is crucial in managing the building energy demand.In this paper,the performance of PV technologies with the mounting methods of Build-ing integrated and Free-standing(Building attached)is discussed for six different climate zone of the country.A PVGIS program proposed with three PV cell technologies(Crystalline Silicon,Copper indium diselenide,Cad-mium Telluride)is used to evaluate monthly energy generation potential and losses of the 2 kW p grid-connected PV system at the latitude and 90°.A 2 kW p PV system is chosen for Economic Weaker Section(EWS)housing schemes depending upon the roof area.From the evaluation,the performance parameter has been estimated.A new parameter Energy Deviation(ED),is proposed to choose the best PV technology in terms of performance.The results of ED agree with the parameters Performance Ratio(PR)and Capacity Factor(CF)defined under the IEC Standard 61724.The potential generation of PV technologies at 90°varies from 41%(Warm and Humid)to 64%(Cold and Sunny)when compared with the latitude.In case of Cold and Sunny and Cold and Cloudy at 90°,the generation performance of Copper indium diselenide is found better in Building integrated and Free-standing mounting methods,respectively.For the remaining zones,Cadmium Telluride technology shows better results.The Percentage loss in the system is found to be minimum in the case of Cold and Sunny,varies between 17%and 25%,and maximum is found for Warm and Humid and varies between 23.2%and 33.4%for the proposed PV technologies.The grid feed-in energy from these EWS houses for all the technologies and climatic zones is found above 45%.It is seen that the combined energy generation from the envelopes(Roof,walls,and facades)makes the houses energy plus in nature.The study has important implications for the government to promote the building integrated Photovoltaic policies in the country.
