Biomass‐derived carbon is a promising electrode material in energy storage devices.However,how to improve its low capacity and stability,and slow diffusion kinetics during lithium storage remains a challenge.In this ...Biomass‐derived carbon is a promising electrode material in energy storage devices.However,how to improve its low capacity and stability,and slow diffusion kinetics during lithium storage remains a challenge.In this research,we propose a“self‐assembly‐template”method to prepare B,N codoped porous carbon(BN‐C)with a nanosandwich structure and abundant pyridinic N‐B species.The nanosandwich structure can increase powder density and cycle stability by constructing a stable solid electrolyte interphase film,shortening the Li^(+) diffusion pathway,and accommodating volume expansion during repeated charging/discharging.The abundant pyridinic N‐B species can simultaneously promote the adsorption/desorption of Li^(+)/PF_(6)^(−) and reduce the diffusion barrier.The BN‐C electrode showed a high lithium‐ion storage capacity of above 1140 mAh g^(−1) at 0.05 A g^(−1) and superior stability(96.5% retained after 2000 cycles).Moreover,owing to the synergistic effect of the nanosandwich structure and pyridinic N‐B species,the assembled symmetrical BN‐C//BN‐C full cell shows a high energy density of 234.7Wh kg^(−1),high power density of 39.38 kW kg−1,and excellent cycling stability,superior to most of the other cells reported in the literature.As the density functional theory simulation demonstrated,pyridinic N‐B shows enhanced adsorption activity for Li^(+) and PF_(6)^(−),which promotes an increase in the capacity of the anode and cathode,respectively.Meanwhile,the relatively lower diffusion barrier of pyridinic N‐B promotes Li^(+) migration,resulting in good rate performance.Therefore,this study provides a new approach for the synergistic modulation of a nanostructure and an active site simultaneously to fabricate the carbon electrode material in energy storage devices.展开更多
At the present stage,China is facing a large number of new risks and challenges in the safety environment,all kinds of environmental pollution problems are widespread,and the atmospheric environmental problems are par...At the present stage,China is facing a large number of new risks and challenges in the safety environment,all kinds of environmental pollution problems are widespread,and the atmospheric environmental problems are particularly prominent.According to the discussion and research of a large number of scholars at home and abroad,a series of factors such as the development of urbanization,economic growth and changes in industrial structure,human consumption,and a large number of large-scale enterprises with high energy consumption are the important reasons for the aggravation of air pollution in our country.Starting with the socio-economic factors closely related to human activities,this paper establishes Sustainability Evaluation using Indicators(SEI),and explores the current situation of the research on the causes of air pollution in China through literature research and summary methods.It not only provides a scientific basis for the reasonable formulation of policies and strategies,but also makes it more convenient for the government to carry out accurate governance on this basis,which is of great significance to the construction of a beautiful China.展开更多
The structural reconstruction mechanism of lignin and cellulose-derived biochars during direct graphitization under ultra-high temperatures was intensively investigated.It was demonstrated that cellulose-derived char ...The structural reconstruction mechanism of lignin and cellulose-derived biochars during direct graphitization under ultra-high temperatures was intensively investigated.It was demonstrated that cellulose-derived char was almost composed of carbon microcrystallites,whereas lignin-derived char reserved some of its skeleton structures,and such structural difference played a vital role in the morphology of formed graphitic layers.The results illustrated that the graphitized lignin-derived sample under 2800℃had graphitic degree of 89.53%,interlayer spacing of 0.3363 nm and electronic conductivity of 104.6 S cm^(−1),while cellulose-derived sample had graphitic degree of 76.74%,layer distance of 0.3374 nm,and electronic conductivity of only 48.8 S cm^(−1).Combined with the results of structural analysis of the chars derived from lignin and cellulose,it was inferred that the stable and aromatic ring containing skeleton structure in lignin was beneficial to the ring-enlarging reconstruction and the formation of large areas of continuous graphitic layers during graphitizing process,leading to high electronic conductivity.Meanwhile,the interwoven microcrystallites in cellulose-derived char strongly restricted the expanding of continuous lamellar graphitic areas even at such ultra-high temperature,causing the formation of turbostratic structure with numerous structural defects as well,and finally resulting in relatively lower electronic conductivity.This work is expected to provide theoretical guidance for preparing high-performance functional carbon materials from lignocellulosic biomass.展开更多
Biochar with a highly accessible specific surface area can display a higher performance when it is used as the cathode of lithium-ion capacitors.Facing the complex composition and diversity of biomass precursors,there...Biochar with a highly accessible specific surface area can display a higher performance when it is used as the cathode of lithium-ion capacitors.Facing the complex composition and diversity of biomass precursors,there is a lack of a universally applicable method to construct hierarchical porous biochar controllably.In this work,a multi-stage activation strategy combining the feature of different activation methods is proposed for this target.To confirm the porous characteristic in prepared samples,N_(2) adsorption-desorption and transmission electron microscope were used.As the optimal sample,BC-P3K4S had the highest specific surface area of 3583.3 m^(2) g^(−1).Evaluated as the electrode for a lithium-ion capacitor,BC-P3K4S displayed a capacity of 139.1 mAh g^(−1) at 0.1 A g^(−1).After coupling it with pre-lithiated hard carbon,the full device exhibited a high energy density of 129.3 W h kg^(−1) at 153 W kg^(−1).The work outlined herein offers some insights into the preparation of hierarchical porous biochar from complex biomass by multistep activation method.展开更多
基金Jiangsu Key Lab of Biomass Energy and Material,Grant/Award Number:JSBEMS‐202101National Natural Science Foundation of China,Grant/Award Numbers:51902162,51902162+4 种基金National Key R&D Program of China,Grant/Award Number:2022YFB4201904Foundation of Jiangsu Key Lab of Biomass Energy and Material,Grant/Award Number:JSBEM‐S‐202101National Key R&D Program,Grant/Award Number:2022YFB4201904Jiangsu Co‐Innovation Center of Efficient Processing and Utilization of Forest Resources,the International Innovation Center for Forest Chemicals and Materialsanjing Forestry University。
文摘Biomass‐derived carbon is a promising electrode material in energy storage devices.However,how to improve its low capacity and stability,and slow diffusion kinetics during lithium storage remains a challenge.In this research,we propose a“self‐assembly‐template”method to prepare B,N codoped porous carbon(BN‐C)with a nanosandwich structure and abundant pyridinic N‐B species.The nanosandwich structure can increase powder density and cycle stability by constructing a stable solid electrolyte interphase film,shortening the Li^(+) diffusion pathway,and accommodating volume expansion during repeated charging/discharging.The abundant pyridinic N‐B species can simultaneously promote the adsorption/desorption of Li^(+)/PF_(6)^(−) and reduce the diffusion barrier.The BN‐C electrode showed a high lithium‐ion storage capacity of above 1140 mAh g^(−1) at 0.05 A g^(−1) and superior stability(96.5% retained after 2000 cycles).Moreover,owing to the synergistic effect of the nanosandwich structure and pyridinic N‐B species,the assembled symmetrical BN‐C//BN‐C full cell shows a high energy density of 234.7Wh kg^(−1),high power density of 39.38 kW kg−1,and excellent cycling stability,superior to most of the other cells reported in the literature.As the density functional theory simulation demonstrated,pyridinic N‐B shows enhanced adsorption activity for Li^(+) and PF_(6)^(−),which promotes an increase in the capacity of the anode and cathode,respectively.Meanwhile,the relatively lower diffusion barrier of pyridinic N‐B promotes Li^(+) migration,resulting in good rate performance.Therefore,this study provides a new approach for the synergistic modulation of a nanostructure and an active site simultaneously to fabricate the carbon electrode material in energy storage devices.
文摘At the present stage,China is facing a large number of new risks and challenges in the safety environment,all kinds of environmental pollution problems are widespread,and the atmospheric environmental problems are particularly prominent.According to the discussion and research of a large number of scholars at home and abroad,a series of factors such as the development of urbanization,economic growth and changes in industrial structure,human consumption,and a large number of large-scale enterprises with high energy consumption are the important reasons for the aggravation of air pollution in our country.Starting with the socio-economic factors closely related to human activities,this paper establishes Sustainability Evaluation using Indicators(SEI),and explores the current situation of the research on the causes of air pollution in China through literature research and summary methods.It not only provides a scientific basis for the reasonable formulation of policies and strategies,but also makes it more convenient for the government to carry out accurate governance on this basis,which is of great significance to the construction of a beautiful China.
基金Fundamental Research Funds of Research Institute of Chemical Industry of Forest Products,CAF(CAFYBB2019SY031)National Key R&D Program(No.2019YFB1503804).
文摘The structural reconstruction mechanism of lignin and cellulose-derived biochars during direct graphitization under ultra-high temperatures was intensively investigated.It was demonstrated that cellulose-derived char was almost composed of carbon microcrystallites,whereas lignin-derived char reserved some of its skeleton structures,and such structural difference played a vital role in the morphology of formed graphitic layers.The results illustrated that the graphitized lignin-derived sample under 2800℃had graphitic degree of 89.53%,interlayer spacing of 0.3363 nm and electronic conductivity of 104.6 S cm^(−1),while cellulose-derived sample had graphitic degree of 76.74%,layer distance of 0.3374 nm,and electronic conductivity of only 48.8 S cm^(−1).Combined with the results of structural analysis of the chars derived from lignin and cellulose,it was inferred that the stable and aromatic ring containing skeleton structure in lignin was beneficial to the ring-enlarging reconstruction and the formation of large areas of continuous graphitic layers during graphitizing process,leading to high electronic conductivity.Meanwhile,the interwoven microcrystallites in cellulose-derived char strongly restricted the expanding of continuous lamellar graphitic areas even at such ultra-high temperature,causing the formation of turbostratic structure with numerous structural defects as well,and finally resulting in relatively lower electronic conductivity.This work is expected to provide theoretical guidance for preparing high-performance functional carbon materials from lignocellulosic biomass.
基金National Natural Science Foundation of China(51976234)Forestry technology projects of Zhejiang Province(2023SY04)+1 种基金Foundation of Jiangsu Key Lab of Biomass Energy and Material(JSBEM-S-202101)National Nonprofit Institute Research Grant of Chinese Academy of Forestry(CAFYBB2020ZF001).
文摘Biochar with a highly accessible specific surface area can display a higher performance when it is used as the cathode of lithium-ion capacitors.Facing the complex composition and diversity of biomass precursors,there is a lack of a universally applicable method to construct hierarchical porous biochar controllably.In this work,a multi-stage activation strategy combining the feature of different activation methods is proposed for this target.To confirm the porous characteristic in prepared samples,N_(2) adsorption-desorption and transmission electron microscope were used.As the optimal sample,BC-P3K4S had the highest specific surface area of 3583.3 m^(2) g^(−1).Evaluated as the electrode for a lithium-ion capacitor,BC-P3K4S displayed a capacity of 139.1 mAh g^(−1) at 0.1 A g^(−1).After coupling it with pre-lithiated hard carbon,the full device exhibited a high energy density of 129.3 W h kg^(−1) at 153 W kg^(−1).The work outlined herein offers some insights into the preparation of hierarchical porous biochar from complex biomass by multistep activation method.