Hard carbon is the most commercially viable anode material for sodium-ion batteries(SIBs),and yet,its practical imple-mentation remains constrained by insufficient low-voltage plateau capacity,a critical parameter gov...Hard carbon is the most commercially viable anode material for sodium-ion batteries(SIBs),and yet,its practical imple-mentation remains constrained by insufficient low-voltage plateau capacity,a critical parameter governing storage capacity.This study introduces a targeted component removal and chemical etching strategy to precisely tailor the porous structure ofhard carbon and thus remarkably enhance the plateau capacity.In this strategy,alkaline-dissolved components are removed toform a closed-pore core with tunable size.Subsequently,the in situ occupied alkaline engineers the pore structure throughchemical etching.The optimized hard carbon material not only has short-range disordered graphite domains to facilitate Na^(+)ions'intercalation and deintercalation but also has abundant micropores and closed-pore structures with appropriate pore sizesand an ultrathin carbon layer(1−3 layers)to significantly increase the sodium storage sites.The resulting hard carbon delivers ahigh reversible specific capacity of 389.6 mAh g^(−1)with a low-voltage plateau capacity as high as up to 261.5 mAh g^(−1)and aninitial Coulombic efficiency of 90.7%.Crucially,this cost-effective methodology shows broad precursor adaptability acrosslignocellulosic biomass,establishing a universal paradigm for designing high-performance carbonaceous anodes for SIBs.展开更多
Alloyed-type anode materials with high-energy density for lithium and sodium ion batteries attracted much attention of the researchers. However, substantial volume expansion of these materials in the devices during re...Alloyed-type anode materials with high-energy density for lithium and sodium ion batteries attracted much attention of the researchers. However, substantial volume expansion of these materials in the devices during repeated electrochemical process leads to fast capacity fading and hinders their further practical application. Nanotechnology could act as a useful tool to effectively address the issue. Herein, lotus-stalk Bi4Ge3O12 nanosheets vertically grown on the nickel foam (denoted as Bi4Ge3O12 NSs@NF) were prepared via a straight-forward solvothermal method. Benefiting from their three dimensional (3D) conductive framework and two dimensional (2D) lotus-stalk Bi4Ge3O12 nanosheet structure, as anode materials of lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs), the electrochemical performances of Bi4Ge3O12 NSs@NF were greatly enhanced as a result of mitigating the huge volume variations during cycles. The Bi4Ge3O12 NSs@NF electrodes delivered a high reversible capacity of 1033.1 mAh/g for the first cycle and exhibited 68.6%capacity retention of after 88 cycles at 0.10 A/g in the voltage window of 0.01~3.0 V versus Li/Li+. In the test of NIBs, the lotus-stalk Bi4Ge3O12 composite electrodes still stored Na+as high as 332.3 mAh/g at 0.10 A/g over 100 sodiation/desodiation repeating cycles.展开更多
With wide application of electric vehicles and large-scale in energy storage systems, the requirement ofsecondary batteries with higher power density and better safety gets urgent. Owing to the merits of hightheoretic...With wide application of electric vehicles and large-scale in energy storage systems, the requirement ofsecondary batteries with higher power density and better safety gets urgent. Owing to the merits of hightheoretical capacity, relatively low cost and suitable discharge voltage, much attention has been paid tothe transition metal sulfides. Recently, a large amount of research papers have reported about the appli-cation of transition metal sulfides in lithium ion batteries. However, the practical application of transitionmetal sulfides is still impeded by their fast capacity fading and poor rate performance. More well-focusedresearches should be operated towards the commercialization of transition metal sulfides in lithium ionbatteries. In this review, recent development of using transition metal sulfides such as copper sulfides,molybdenum sulfides, cobalt sulfides, and iron sulfides as electrode materials for lithium ion batteriesis presented. In addition, the electrochemical reaction mechanisms and synthetic strategy of transitionmetal sulfides are briefly summarized. The critical issues, challenges, and perspectives providing a fur-ther understanding of the associated electrochemical processes are also discussed.展开更多
To study the dynamic response of vertical and batter pile groups in saturated sand,dynamic tests of these pile groups in saturated sand were carried out using the ZJU400 geotechnical centrifuge at Zhejiang University....To study the dynamic response of vertical and batter pile groups in saturated sand,dynamic tests of these pile groups in saturated sand were carried out using the ZJU400 geotechnical centrifuge at Zhejiang University.The following results were obtained.(1)As the motion intensity increased,the peak acceleration in soil layers at different depths significantly decreased,indicating that the soil stiffness was significantly reduced.(2)During the motion process,the instantaneous bending moment of the vertical and batter pile groups at different depths changed continuously,which had a strong relationship with the saturated sand liquefaction.In the process of sand liquefaction,the residual bending moment generated by the batter pile was more obvious than that of the vertical pile.(3)With the liquefaction of the saturated sand,the distribution of the maximum bending moment of the vertical pile group changed,and the bending moment near the pile cap of the vertical and batter pile groups was always large.(4)In certain cases,the horizontal acceleration and dynamic displacement of the vertical pile cap were amplified.When the motion intensity was large,residual displacement of the batter pile cap occurred.展开更多
Offshore jacket-type platforms are attached to the seabed by long batter piles. In this paper, results from a finite element analysis, verified against experimental data, are used to study the effect of the pile＇s in...Offshore jacket-type platforms are attached to the seabed by long batter piles. In this paper, results from a finite element analysis, verified against experimental data, are used to study the effect of the pile＇s inclination angle, and its interaction with the geometrical properties of the pile and the geotechnical characteristics of the surrounding soil on the behavior of the inclined piles supporting the jacket platforms. Results show that the inclination angle is one of the main parameters affecting the behavior of an offshore pile. We investigated the effect of the inclination angle on the maximum von Mises stress, maximum von Mises elastic strain, maximum displacement vector sum, maximum displacement in the horizontal direction, and maximum displacement in the vertical direction. Results indicate that the pile＇s operationally optimal degree of inclination is approximately 5°. By exceeding this value, the instability in the surrounding soil under applied loads grows extensively in all the geotechnical properties considered. Cohesive soils tend to display poorer results compared to grained soils.展开更多
Micropiles are drilled and grouted piles having diameter between 100 to 250 mm. Due to its small diameter, it is suitable for low headroom and limited work area conditions. It can be installed without noise nuisance, ...Micropiles are drilled and grouted piles having diameter between 100 to 250 mm. Due to its small diameter, it is suitable for low headroom and limited work area conditions. It can be installed without noise nuisance, without vibrations to surrounding soils and structures and without disruption to the production operations in industries which makes micropiles suitable for underpinning and seismic retrofitting of structures. It is necessary to therefore understand the behaviour of micropiles under different loading conditions. This work is on vertical and battered micropiles with different length/diameter ratio (L/D) subjected to vertical and lateral loading conditions. Batter angles had a significant influence on both the vertical and lateral load carrying capacity. The ultimate vertical load was found to increase upto a 30°batter. The ultimate lateral load was found to increase significantly with increasing L/D ratios upto an L/D ratio of 30 for vertical and 48 for battered piles, beyond which the increase was found to be not significant. In general, negative battered micropiles offered more lateral resistance than positive battered micropiles. The results of the study indicated that the ultimate load capacity and mode of failure of the micropiles are a function of the angle of batter, direction of batter and the L/D ratio for vertically and laterally loaded micropiles.展开更多
A comparative study of the seismic performance of 2×1 pile groups considering different degrees of batter(0°for vertical,10°and 20°)embedded in single homogeneous liquefiable sand through fully cou...A comparative study of the seismic performance of 2×1 pile groups considering different degrees of batter(0°for vertical,10°and 20°)embedded in single homogeneous liquefiable sand through fully coupled three-dimensional dynamic analyses is presented.The effects of inertial interaction are considered with structures having two different periods.The performance of pile groups is investigated for the fixed and pinned pile to cap connections for both floating and end bearing types of pile groups.Slenderness ratios of piles were also varied to enable a comprehensive understanding.Investigations have been carried out for three earthquake motions having varied dominant frequencies.It is observed that batter pile groups in liquefiable soils provide beneficial effects on piles and superstructure responses for both fixed and pinned head pile to cap connections for long period structures.However,for short period structures,a beneficial effect is most evident for fixed head connection.展开更多
In order to ensure that the lithium-ion battery pack keeps good working performance during the driving of electric vehicle,the heat generation mechanism and heat transfer characteristics of lithium-ion battery are ana...In order to ensure that the lithium-ion battery pack keeps good working performance during the driving of electric vehicle,the heat generation mechanism and heat transfer characteristics of lithium-ion battery are analyzed.The power battery pack of electric vehicle is simulated by advanced vehicle simulator.The simulation results of battery pack current under typical cycle conditions and the heat source curve of lithium ion battery are obtained,which provide data for the simulation of heat source input of battery temperature field.On this basis,the flow field and temperature field of the original lithium-ion battery pack of electric vehicle are simulated by using computational fluid dynamics method.The influence of different air passage spacing and air inlet angle on the temperature field of lithium ion battery pack was analyzed.The optimization scheme of heat dissipation structure of lithium ion battery pack was put forward,and the numerical simulation analysis of the optimization scheme was carried out.The results show that the heat dissipation effect of the heat dissipation structure is obviously improved by choosing the appropriate air inlet and the combined air passage spacing,and it is beneficial to the uniformity of the temperature of the single battery.The maximum temperature of the battery pack is reduced by 3.8℃,and the temperature difference of the battery pack is reduced by 2.2℃.展开更多
La_(4)NiLiO_(8)-coated NCM622 samples were prepared through a sol-gel method,and the electrochemical performance as cathode materials was investigated.It is revealed that part of the introduced La^(3+)ions produce a c...La_(4)NiLiO_(8)-coated NCM622 samples were prepared through a sol-gel method,and the electrochemical performance as cathode materials was investigated.It is revealed that part of the introduced La^(3+)ions produce a coating layer on the surface of NCM622 particles,while the rest occupy the 3b position of the lattice.The optimized sample exhibits a capacity retention of 96.54%after 100 cycles under 1C rate with a discharge specific capacity of 117.54 mAh·g^(-1)under 5C rate,much higher than those of the unmodified sample.The results show that the addition of La^(3+)ion can greatly improve the cyclic stability and the rate performance of NCM622.展开更多
In permafrost regions with warm frozen soil,subgrade thaw-collapse phenomenon commonly occurs,facing thaw collapse problems of the existed frozen soil subgrade,thus it is difficult to use traditional methods such as a...In permafrost regions with warm frozen soil,subgrade thaw-collapse phenomenon commonly occurs,facing thaw collapse problems of the existed frozen soil subgrade,thus it is difficult to use traditional methods such as active cooling and passive protection technology to stabilize the existed warm frozen soil subgrade.This study derives a novel stabilizer method,a long-short(L-S)cement-mixed batter pile composite foundation to stabilize the existed warm frozen soil subgrade.To solve the thawcollapse problems in warm frozen soil subgrade,high water content and large compressibility characteristics were compared between soft soil and warm frozen soils.Theoretical analysis of heat conduction and numerical simulation of finite element model were used to study the freeze–thaw process and evaluate the stabilized effects of the L-S cement-mixed batter piles on the warm frozen soil foundation of the Qinghai-Xizang Highway.Furthermore,the thaw process and mechanical properties of foundation and piles were analyzed by introducing the hydration heat factor in the thermodynamic control equation.The results indicate that the thawing displacement of the existed warm frozen soil subgrade was reduced owing to the“support”and“grasp”effects of the L-S cement-mixed batter piles on the surrounding soil.The composite ground formed by strengthening the warm frozen ground with batter piles could considerably improve the bearing capacity of the existed warm frozen ground,effectively restrain the deformation of the upper embankment,and improve the strength of the ground.The analysis can provide method for the construction design of cement mixing batter pile foundation in cold regions.展开更多
基金the National Key Research and Development Program(2023YFE0109600)the State Key Laboratory of Advanced Papermaking and Paper-based Materials(2023PY03,2023C07,and 2024ZD02)the Central Guidance Fund for Local Scientific and TechnologicalDevelopment(2024ZY0012)。
文摘Hard carbon is the most commercially viable anode material for sodium-ion batteries(SIBs),and yet,its practical imple-mentation remains constrained by insufficient low-voltage plateau capacity,a critical parameter governing storage capacity.This study introduces a targeted component removal and chemical etching strategy to precisely tailor the porous structure ofhard carbon and thus remarkably enhance the plateau capacity.In this strategy,alkaline-dissolved components are removed toform a closed-pore core with tunable size.Subsequently,the in situ occupied alkaline engineers the pore structure throughchemical etching.The optimized hard carbon material not only has short-range disordered graphite domains to facilitate Na^(+)ions'intercalation and deintercalation but also has abundant micropores and closed-pore structures with appropriate pore sizesand an ultrathin carbon layer(1−3 layers)to significantly increase the sodium storage sites.The resulting hard carbon delivers ahigh reversible specific capacity of 389.6 mAh g^(−1)with a low-voltage plateau capacity as high as up to 261.5 mAh g^(−1)and aninitial Coulombic efficiency of 90.7%.Crucially,this cost-effective methodology shows broad precursor adaptability acrosslignocellulosic biomass,establishing a universal paradigm for designing high-performance carbonaceous anodes for SIBs.
基金supported by the National Natural science Foundation of China (No. U1804138)the Science Foundation of Henan Province (No. 162300410209)+1 种基金the Key Scientific Research Project of High Schools in Henan Province (No. 17A480009)the Special Key Research Program of Henan Province (No. 182102210488)
文摘Alloyed-type anode materials with high-energy density for lithium and sodium ion batteries attracted much attention of the researchers. However, substantial volume expansion of these materials in the devices during repeated electrochemical process leads to fast capacity fading and hinders their further practical application. Nanotechnology could act as a useful tool to effectively address the issue. Herein, lotus-stalk Bi4Ge3O12 nanosheets vertically grown on the nickel foam (denoted as Bi4Ge3O12 NSs@NF) were prepared via a straight-forward solvothermal method. Benefiting from their three dimensional (3D) conductive framework and two dimensional (2D) lotus-stalk Bi4Ge3O12 nanosheet structure, as anode materials of lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs), the electrochemical performances of Bi4Ge3O12 NSs@NF were greatly enhanced as a result of mitigating the huge volume variations during cycles. The Bi4Ge3O12 NSs@NF electrodes delivered a high reversible capacity of 1033.1 mAh/g for the first cycle and exhibited 68.6%capacity retention of after 88 cycles at 0.10 A/g in the voltage window of 0.01~3.0 V versus Li/Li+. In the test of NIBs, the lotus-stalk Bi4Ge3O12 composite electrodes still stored Na+as high as 332.3 mAh/g at 0.10 A/g over 100 sodiation/desodiation repeating cycles.
基金the financial support of the National Natural Science Foundation of China (21273185 and 21621091)the National Found for Fostering Talents of Basic Science (J1310024)
文摘With wide application of electric vehicles and large-scale in energy storage systems, the requirement ofsecondary batteries with higher power density and better safety gets urgent. Owing to the merits of hightheoretical capacity, relatively low cost and suitable discharge voltage, much attention has been paid tothe transition metal sulfides. Recently, a large amount of research papers have reported about the appli-cation of transition metal sulfides in lithium ion batteries. However, the practical application of transitionmetal sulfides is still impeded by their fast capacity fading and poor rate performance. More well-focusedresearches should be operated towards the commercialization of transition metal sulfides in lithium ionbatteries. In this review, recent development of using transition metal sulfides such as copper sulfides,molybdenum sulfides, cobalt sulfides, and iron sulfides as electrode materials for lithium ion batteriesis presented. In addition, the electrochemical reaction mechanisms and synthetic strategy of transitionmetal sulfides are briefly summarized. The critical issues, challenges, and perspectives providing a fur-ther understanding of the associated electrochemical processes are also discussed.
基金National Natural Science Foundation of China under Grant No.51778207,Natural Science Foundation of Hebei Province under Grant No.E2018202107,Project of Graduate Students′Innovative Ability Training of Hebei Province under Grant No.CXZZBS2019041。
文摘To study the dynamic response of vertical and batter pile groups in saturated sand,dynamic tests of these pile groups in saturated sand were carried out using the ZJU400 geotechnical centrifuge at Zhejiang University.The following results were obtained.(1)As the motion intensity increased,the peak acceleration in soil layers at different depths significantly decreased,indicating that the soil stiffness was significantly reduced.(2)During the motion process,the instantaneous bending moment of the vertical and batter pile groups at different depths changed continuously,which had a strong relationship with the saturated sand liquefaction.In the process of sand liquefaction,the residual bending moment generated by the batter pile was more obvious than that of the vertical pile.(3)With the liquefaction of the saturated sand,the distribution of the maximum bending moment of the vertical pile group changed,and the bending moment near the pile cap of the vertical and batter pile groups was always large.(4)In certain cases,the horizontal acceleration and dynamic displacement of the vertical pile cap were amplified.When the motion intensity was large,residual displacement of the batter pile cap occurred.
文摘Offshore jacket-type platforms are attached to the seabed by long batter piles. In this paper, results from a finite element analysis, verified against experimental data, are used to study the effect of the pile＇s inclination angle, and its interaction with the geometrical properties of the pile and the geotechnical characteristics of the surrounding soil on the behavior of the inclined piles supporting the jacket platforms. Results show that the inclination angle is one of the main parameters affecting the behavior of an offshore pile. We investigated the effect of the inclination angle on the maximum von Mises stress, maximum von Mises elastic strain, maximum displacement vector sum, maximum displacement in the horizontal direction, and maximum displacement in the vertical direction. Results indicate that the pile＇s operationally optimal degree of inclination is approximately 5°. By exceeding this value, the instability in the surrounding soil under applied loads grows extensively in all the geotechnical properties considered. Cohesive soils tend to display poorer results compared to grained soils.
文摘Micropiles are drilled and grouted piles having diameter between 100 to 250 mm. Due to its small diameter, it is suitable for low headroom and limited work area conditions. It can be installed without noise nuisance, without vibrations to surrounding soils and structures and without disruption to the production operations in industries which makes micropiles suitable for underpinning and seismic retrofitting of structures. It is necessary to therefore understand the behaviour of micropiles under different loading conditions. This work is on vertical and battered micropiles with different length/diameter ratio (L/D) subjected to vertical and lateral loading conditions. Batter angles had a significant influence on both the vertical and lateral load carrying capacity. The ultimate vertical load was found to increase upto a 30°batter. The ultimate lateral load was found to increase significantly with increasing L/D ratios upto an L/D ratio of 30 for vertical and 48 for battered piles, beyond which the increase was found to be not significant. In general, negative battered micropiles offered more lateral resistance than positive battered micropiles. The results of the study indicated that the ultimate load capacity and mode of failure of the micropiles are a function of the angle of batter, direction of batter and the L/D ratio for vertically and laterally loaded micropiles.
基金Ministry of Earth Sciences,Govt.of India,for Providing Financial Assistance for the Research(Project No.MoES/P.O.(Seismo)/1(303)/2017)。
文摘A comparative study of the seismic performance of 2×1 pile groups considering different degrees of batter(0°for vertical,10°and 20°)embedded in single homogeneous liquefiable sand through fully coupled three-dimensional dynamic analyses is presented.The effects of inertial interaction are considered with structures having two different periods.The performance of pile groups is investigated for the fixed and pinned pile to cap connections for both floating and end bearing types of pile groups.Slenderness ratios of piles were also varied to enable a comprehensive understanding.Investigations have been carried out for three earthquake motions having varied dominant frequencies.It is observed that batter pile groups in liquefiable soils provide beneficial effects on piles and superstructure responses for both fixed and pinned head pile to cap connections for long period structures.However,for short period structures,a beneficial effect is most evident for fixed head connection.
文摘In order to ensure that the lithium-ion battery pack keeps good working performance during the driving of electric vehicle,the heat generation mechanism and heat transfer characteristics of lithium-ion battery are analyzed.The power battery pack of electric vehicle is simulated by advanced vehicle simulator.The simulation results of battery pack current under typical cycle conditions and the heat source curve of lithium ion battery are obtained,which provide data for the simulation of heat source input of battery temperature field.On this basis,the flow field and temperature field of the original lithium-ion battery pack of electric vehicle are simulated by using computational fluid dynamics method.The influence of different air passage spacing and air inlet angle on the temperature field of lithium ion battery pack was analyzed.The optimization scheme of heat dissipation structure of lithium ion battery pack was put forward,and the numerical simulation analysis of the optimization scheme was carried out.The results show that the heat dissipation effect of the heat dissipation structure is obviously improved by choosing the appropriate air inlet and the combined air passage spacing,and it is beneficial to the uniformity of the temperature of the single battery.The maximum temperature of the battery pack is reduced by 3.8℃,and the temperature difference of the battery pack is reduced by 2.2℃.
基金Funded by the Guangdong Key R&D Program(Nos.2020B 0909040001 and 2019B090909003)。
文摘La_(4)NiLiO_(8)-coated NCM622 samples were prepared through a sol-gel method,and the electrochemical performance as cathode materials was investigated.It is revealed that part of the introduced La^(3+)ions produce a coating layer on the surface of NCM622 particles,while the rest occupy the 3b position of the lattice.The optimized sample exhibits a capacity retention of 96.54%after 100 cycles under 1C rate with a discharge specific capacity of 117.54 mAh·g^(-1)under 5C rate,much higher than those of the unmodified sample.The results show that the addition of La^(3+)ion can greatly improve the cyclic stability and the rate performance of NCM622.
基金supported by the National Natural Science Foundation of China(Grant No.41971086)Natural Science Foundation of Shanxi Province(Grant No.2023-JC-QN-0626,2022JQ-467).
文摘In permafrost regions with warm frozen soil,subgrade thaw-collapse phenomenon commonly occurs,facing thaw collapse problems of the existed frozen soil subgrade,thus it is difficult to use traditional methods such as active cooling and passive protection technology to stabilize the existed warm frozen soil subgrade.This study derives a novel stabilizer method,a long-short(L-S)cement-mixed batter pile composite foundation to stabilize the existed warm frozen soil subgrade.To solve the thawcollapse problems in warm frozen soil subgrade,high water content and large compressibility characteristics were compared between soft soil and warm frozen soils.Theoretical analysis of heat conduction and numerical simulation of finite element model were used to study the freeze–thaw process and evaluate the stabilized effects of the L-S cement-mixed batter piles on the warm frozen soil foundation of the Qinghai-Xizang Highway.Furthermore,the thaw process and mechanical properties of foundation and piles were analyzed by introducing the hydration heat factor in the thermodynamic control equation.The results indicate that the thawing displacement of the existed warm frozen soil subgrade was reduced owing to the“support”and“grasp”effects of the L-S cement-mixed batter piles on the surrounding soil.The composite ground formed by strengthening the warm frozen ground with batter piles could considerably improve the bearing capacity of the existed warm frozen ground,effectively restrain the deformation of the upper embankment,and improve the strength of the ground.The analysis can provide method for the construction design of cement mixing batter pile foundation in cold regions.
