As important ingredients in lithium-ion battery,the Coulombic efficiency and power density greatly impact the electrochemical performances.Although recent literatures have reported nano-porous materials to enhance the...As important ingredients in lithium-ion battery,the Coulombic efficiency and power density greatly impact the electrochemical performances.Although recent literatures have reported nano-porous materials to enhance the specific capacities,intrinsic drawbacks such as poor initial Coulombic efficiency and low volumetric capacity could not be avoided.Herein,we propose a strategy to prepare carbon supported MoO_(2)spheres used for lithium-ion battery with high volumetric capacity density.A high initial Coulombic efficiency of 76.5%is obtained due to limited solid electrolyte interface film formed on the exposed surface.Meantime,the sample with an optimal carbon content and a proper structural strength reveals a higher reversible capacity of 956 mA h g^(-1)than the theoretical capacity of crystalline Mo O_(2)(838 mA h g^(-1))and a high capacity retention ratio of 96.4%after 100 cycles at 0.5 A g^(-1).And an effective compaction capacity density(under 5 MPa)of 670 mA h cm^(-3)of the spheres proves its potential value in practical applications.展开更多
Lithium-and manganese-rich(LMR)layered cathode materials hold the great promise in designing the next-generation high energy density lithium ion batteries.However,due to the severe surface phase transformation and str...Lithium-and manganese-rich(LMR)layered cathode materials hold the great promise in designing the next-generation high energy density lithium ion batteries.However,due to the severe surface phase transformation and structure collapse,stabilizing LMR to suppress capacity fade has been a critical challenge.Here,a bifunctional strategy that integrates the advantages of surface modification and structural design is proposed to address the above issues.A model compound Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)(MNC)with semi-hollow microsphere structure is synthesized,of which the surface is modified by surface-treated layer and graphene/car-bon nanotube dual layers.The unique structure design enabled high tap density(2.1 g cm^(−3))and bidirectional ion diffusion pathways.The dual surface coatings covalent bonded with MNC via C-O-M linkage greatly improves charge transfer efficiency and mitigates electrode degradation.Owing to the synergistic effect,the obtained MNC cathode is highly conformal with durable structure integrity,exhibiting high volumetric energy density(2234 Wh L^(−1))and predominant capacitive behavior.The assembled full cell,with nanograph-ite as the anode,reveals an energy density of 526.5 Wh kg^(−1),good rate performance(70.3%retention at 20 C)and long cycle life(1000 cycles).The strategy presented in this work may shed light on designing other high-performance energy devices.展开更多
BACKGROUND The association between body mass index(BMI)and bone mineral density(BMD)has shown inconsistent results,varying by sex and skeletal site.Despite normal or elevated bone mass,individuals with type 2 diabetes...BACKGROUND The association between body mass index(BMI)and bone mineral density(BMD)has shown inconsistent results,varying by sex and skeletal site.Despite normal or elevated bone mass,individuals with type 2 diabetes have an increased risk of hip and vertebral fractures.AIM To assess lumbar spine trabecular volumetric BMD(vBMD)across different BMI categories in individuals with and without diabetes.METHODS This cross-sectional study included 966 men over 50 years old and 1001 postmenopausal women from the Pinggu Metabolic Disease Study.The vBMD of lumbar vertebrae 2 through 4 was measured using quantitative computed tomography.Total adipose tissue,subcutaneous adipose tissue(SAT),visceral adipose tissue(VAT),and lumbar skeletal muscle area were also quantified.RESULTS In men with obesity(P=0.038)and overweight(P=0.032),vBMD was significantly higher in the diabetes group compared to non-diabetic men.After adjusting for age and sex,no significant saturation effect between BMI and BMD was found in participants with diabetes or in women without diabetes.However,a BMI threshold of 22.33 kg/m²indicated a saturation point for vBMD in nondiabetic men.Independent predictors of vBMD in men included age(r=-0.387,P<0.001),BMI(r=0.130,P=0.004),and VAT(r=-0.145,P=0.001).For women,significant predictors were age(r=-0.594,P<0.001),BMI(r=0.157,P=0.004),VAT(r=-0.112,P=0.001),and SAT(r=-0.068,P=0.035).CONCLUSION The relationship between BMI and trabecular vBMD differs in individuals with and without diabetes.Overweight and obese men with diabetes exhibit higher vBMD.展开更多
Zinc-ion hybrid super-capacitors are regarded as promising safe energy storage systems,However,the relatively low volumetric energy density has become the main bottlenecks in practical applications of portable electro...Zinc-ion hybrid super-capacitors are regarded as promising safe energy storage systems,However,the relatively low volumetric energy density has become the main bottlenecks in practical applications of portable electronic devices,In this work,the zinc-ion hybrid super-capacitor with high volumetric energy density and superb cycle stability had been constructed which employing the high-density threedimensional graphene hydrogel as cathode and Zn foil used as anode in 1 mol/L ZnSO4 electrolyte.Benefiting from the abundant ion transport paths and the abundant active sites for graphene hydrogel with high density and porous structure,the zinc-ion hybrid super-capacitor exhibited an extremely high volumetric energy density of 118.42 Wh/L and a superb power density of 24.00 kW/L,as well as an excellent long cycle life(80% retention after 30,000 cycles at 10 A/g),which was superior to the volumetric energy density of the reported zinc-ion hybrid super-capacitors.This device,based on the fast ion adsorption/deso rption on the capacitor-type graphene cathode and reversible Zn^(2+) plating/stripping on the battery-type Zn anode,which will inspire the development of zinc-ion hybrid super-capacitor in miniaturized devices.展开更多
In the pursuit of carbon neutrality,hydrogen(H_(2))is often hailed as the ideal fuel for fuel cell vehicles(FCVs)due to its zero-emission nature and high gravimetric energy density.However,its low volumetric density n...In the pursuit of carbon neutrality,hydrogen(H_(2))is often hailed as the ideal fuel for fuel cell vehicles(FCVs)due to its zero-emission nature and high gravimetric energy density.However,its low volumetric density necessitates high-pressure on-board storage(up to 700 bar),which are costly and pose significant safety risks.To cope with these challenges,the U.S.Department of energy(DOE)has set ambitious targets for hydrogen storage systems,aiming for a gravimetric capacity of 6.5 wt%with a volumetric capacity of 50 g L^(-1).Porous crystals,exemplified by metal-organic frameworks(MOFs)[1,2],covalent organic frameworks(COFs),and hydrogen-bonded organic frameworks(HOFs)[3],have shown promise for hydrogen storage at 77 K with delivery at 160 K under significantly lower pressures(≤100 bar).展开更多
The scientific article examines the physical and mechanical properties of raw cotton stored in buntings in cotton palaces. Because during the storage of raw cotton in bunts, some of its properties deteriorate, some im...The scientific article examines the physical and mechanical properties of raw cotton stored in buntings in cotton palaces. Because during the storage of raw cotton in bunts, some of its properties deteriorate, some improvements. Therefore, the mathematical modeling of storage conditions of raw cotton in bunts and the physical and mechanical conditions that occur in it is of great importance. In the developed mathematical model, the main factor influencing the physical and mechanical properties of raw cotton is the change in temperature. Due to the temperature, kinetic and biological processes accumulated in the raw cotton in Bunt, it can spread over a large surface, first in a small-local state, over time with a nonlinear law. As a result, small changes in temperature lead to a qualitative change in physical properties. In determining the law of temperature distribution in the raw cotton in Bunt, Laplace’s differential equation of heat transfer was used. The differential equation of heat transfer in Laplace’s law was replaced by a system of ordinary differential equations by approximation. Conditions are solved in MAPLE-17 program by numerical method. As a result, graphs of temperature changes over time in raw cotton were obtained. In addition, the table shows the changes in density, pressure and mass of cotton, the height of the bun. As the density of the cotton raw material increases from the top layer of the bunt to the bottom layer, an increase in the temperature in it has been observed. This leads to overheating of the bottom layer of cotton and is the main reason for the deterioration of the quality of raw materials.展开更多
High volumetric power density （VPD） is the basis for the commercial success of micro-tubular solid oxide fuel cells （mtSOFCs）. To find maximal VPD （MVPD） for anode-supported mtSOFC （as-mtSOFC）, the effects of ...High volumetric power density （VPD） is the basis for the commercial success of micro-tubular solid oxide fuel cells （mtSOFCs）. To find maximal VPD （MVPD） for anode-supported mtSOFC （as-mtSOFC）, the effects of geometric parameters on VPD are analyzed and the anode thickness, tan, and the cathode length, lea, are identified as the key design parameters. Thermo-fluid electrochemical models were built to examine the dependence of the electrical output on the cell parameters. The multiphysics model is validated by reproducing the experimental I-V curves with no adjustable parameters. The optimal lea and the corresponding MVPDs are then determined by the multiphysics model for 20 combinations of rin, the inner tube radius, and tan. And all these optimization are made at 1073.15 K. The results show that： （i） significant performance improvement may be achieved by geometry optimization, （ii） the seemingly high MVPD of 11 and 14 W/cm^3 can be easily realized for as-mtSOFC with single- and double-terminal anode current collection, respectively. Moreover, the variation of the area specific power density with/cac（2 mm, 40 mm） is determined for three representative （tin, tan） combinations. Besides, it is demonstrated that the current output of mtSOFC with proper geometric parameters is comparable to that of planar SOFC.展开更多
LiFePO4/C microspheres with different surface morphologies and porosities were prepared from different carbon sources. The effects of the surface morphology and pore structure of the microspheres on their electrochemi...LiFePO4/C microspheres with different surface morphologies and porosities were prepared from different carbon sources. The effects of the surface morphology and pore structure of the microspheres on their electrochemical properties and electrode density were investigated. The electrochemical performance and electrode density depended on the morphology and pore structure of the LiFePO4/C microspheres. Open-pore LiFePO4/C microspheres with rough surfaces exhibited good adhesion with current collectors and a high electrode density （2.6g/cm3）. They also exhibited high performance in a half cell and full battery with a high volumetric energy density.展开更多
Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand.However,studies on lithium primary batteries are currently focused on the gravimetric energy...Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand.However,studies on lithium primary batteries are currently focused on the gravimetric energy densities of active materials and rarely account for the volumetric energy requirements of unmanned devices.Herein,CuF_(2)/CF_(x) composites are prepared via planetary ball milling(PBM)to improve the volumetric energy densities of lithium primary batteries using the high mass density of CuF_(2),achieving a maximum volumetric energy density of 4163.40 Wh L^(-1).The CuF_(2)/CF_(x) hybrid cathodes exhibit three distinct discharge plateaus rather than simple combinations of the discharge curves of their components.This phenomenon is caused by charge redistribution and lattice modulation on the contact surfaces of CuF_(2) and CF_(x) during PBM,which change the valence state of Cu and modify the electronic structures of the composites.As a result,CuF_(2)/CF_(x) hybrid cathodes exhibit unique discharge behaviors and improved rate capabilities,delivering a maximum power density of 11.16 kW kg^(-1)(25.56 kW L^(-1)).Therefore,it is a promising strategy to further improve the comprehensive performance of lithium primary batteries through the use of interfacial optimization among different fluoride cathodes.展开更多
Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets ...Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm^(-2)as cathode and anode at 2 mA cm^(-2),and 79.5%and 80%capacity have been preserved at 50 mA cm^(-2).In the meantime,they all showed excellent cycling performance with negligible change after>10000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm^(-2)and 0.352 mW cm^(-3)).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.展开更多
Electronic textiles hold the merits of high conformability with the human body and natural surrounding,possessing large market demand and wide application foreground in smart wearable and portable devices.However,thei...Electronic textiles hold the merits of high conformability with the human body and natural surrounding,possessing large market demand and wide application foreground in smart wearable and portable devices.However,their further application is largely hindered by the shortage of flexible and stable power sources with multifunctional designability.Herein,a free-standing ZnHCF@CF electrode(ZnHCF grown on carbon nanotube fiber)with good mechanical deformability and high electrochemical performance for aqueous fiber-shaped calcium ion battery(FCIB)is reported.Benefiting from the unique Ca^(2+)/H^(+)co-insertion mechanism,the ZnHCF@CF cathode can exhibit great ion storage capability within a broadened voltage window.By pairing with a polyaniline(PANI)@CF anode,a ZnHCF@CF//PANI@CF FCIB is successfully fabricated,which exhibits a desirable volumetric energy density of 43.2mWh cm^(-3)and maintains superior electrochemical properties under different deformations.Moreover,the high-energy FCIB can be harmoniously integrated with a fiber-shaped strain sensor(FSS)to achieve real-time physiological monitoring on knees during long-running,exhibiting great promise for the practical application of electronic textiles.展开更多
Although the gravimetric energy density of lithium-sulfur battery is very encouraging,the volumetric energy density still remains a challenge for the practical application.To achieve the high volumetric energy density...Although the gravimetric energy density of lithium-sulfur battery is very encouraging,the volumetric energy density still remains a challenge for the practical application.To achieve the high volumetric energy density of battery,much attention should be paid to the sulfur cathode.Herein,we introduce heavy lithium cobalt oxide(LiCoO_(2))nanofibers as sulfur host to enhance the volumetric capacity of cathode,maintaining the high gravimetric capacity simutaneously.With the high tap density of 2.26 g cm^(−3),LiCoO_(2)nanofibers can be used to fabricate a really compact sulfur cathode,with a density and porosity of 0.85 g cm^(−3)and 61.2%,respectively.More importantly,LiCoO2 nanofibers could act as an efficient electrocatalyst for enhancing the redox kinetics of sulfur species,ensuring the cathode electroactivity and alleviating the shuttle effect of polysulfides.Therefore,a balance between compact structure and high electrochemical activity is obtained for the sulfur cathode.At the sulfur loading of 5.1 mg cm^(−2),high volumetric and gravimetric capacities of 724 mA h cm^(−3)cathode and 848 mA h g^(−1)cathode could be achieved based on the cathode volume and weight,respectively.Moreover,with this efficient S/LiCoO_(2)cathode,the lithium corrosion by polysulfides is supressed,leading to a more stable lithium anode.展开更多
Potassium ion batteries(PIBs)with high-volumetric energy densities are promising for next-generation low-cost energy storage devices.Metallic bismuth(Bi)with a structure similar to graphite,is a promising anode materi...Potassium ion batteries(PIBs)with high-volumetric energy densities are promising for next-generation low-cost energy storage devices.Metallic bismuth(Bi)with a structure similar to graphite,is a promising anode material for PIBs due to its high theoretical volumetric capacity(3763 mA h cm^−3)and relatively low working potential(−2.93 V vs.standard hydrogen electrode).However,it experiences severe capacity decay caused by a huge volume expansion of Bi when alloying with potassium.This study reports a flexible and free-standing Bi nanosheet(BiNS)/reduced graphene oxide composite membrane with designed porosity close to the expansion ratio of BiNS after charging.The controlled pore structure improves the electron and ion transport during cycling,and strengthens the structural stability of the electrode during potassiation and depotassiation,leading to excellent electrochemical performance for potassium-ion storage.In particular,it delivers a high reversible volumetric capacity of 451 mA h cm^−3 at the current density of 0.5 A g^−1,which is much higher than the previously reported commercial graphite material.展开更多
Although lithium-rich manganese-based(LRM)cathode materials have high capacity(>250 mAh g^(-1))due to their multi-electron redox mechanisms and offer cost advantages due to their high Mn content,challenges remain b...Although lithium-rich manganese-based(LRM)cathode materials have high capacity(>250 mAh g^(-1))due to their multi-electron redox mechanisms and offer cost advantages due to their high Mn content,challenges remain before they can achieve commercialization as replacements for lithium cobalt oxides which have high volumetric energy density.Here,we construct a hierarchically structured LRM cathode,featuring primary micro-bricks and abundant exposure of lithium-ion active transport facets({010}planes).Benefiting from these densely packed bricks and rapid lithium-ion active planes,the hierarchical material achieves an optimal compaction density of 3.4 g cm^(-3) and an ultrahigh volumetric energy density of 3431.0 Wh L^(-1),which is the highest performance level to date.Advanced characterizations,including hard X-ray absorption spectra and wide-angle X-ray scattering spectra,combined with density functional theory calculations,demonstrate that the hierarchical material shows a highly reversible charge compensation process and low-strain structural evolution.In addition,when the material has appropriate Li/Ni intermixing,it is not prone to shearing or sliding along the two-dimensional lithium-ion diffusion planes,which promotes robust architectural stability under high-pressure calendering and long-term cycling.This work should promote the development of advanced cathode materials for rechargeable batteries with high volumetric energy density.展开更多
基金financially supported by the National Natural Science Foundation of China(21975250)the National Key R&D Program of China(2017YFE0198100)+1 种基金the Hightech Research Key laboratory of Zhenjiang(SS2018002)Jiangsu Post-doctoral Research Funding Program(2020Z257)。
文摘As important ingredients in lithium-ion battery,the Coulombic efficiency and power density greatly impact the electrochemical performances.Although recent literatures have reported nano-porous materials to enhance the specific capacities,intrinsic drawbacks such as poor initial Coulombic efficiency and low volumetric capacity could not be avoided.Herein,we propose a strategy to prepare carbon supported MoO_(2)spheres used for lithium-ion battery with high volumetric capacity density.A high initial Coulombic efficiency of 76.5%is obtained due to limited solid electrolyte interface film formed on the exposed surface.Meantime,the sample with an optimal carbon content and a proper structural strength reveals a higher reversible capacity of 956 mA h g^(-1)than the theoretical capacity of crystalline Mo O_(2)(838 mA h g^(-1))and a high capacity retention ratio of 96.4%after 100 cycles at 0.5 A g^(-1).And an effective compaction capacity density(under 5 MPa)of 670 mA h cm^(-3)of the spheres proves its potential value in practical applications.
基金The authors greatly appreciate the financial support from the National Science Foundation of China(22075048,51173027,21875141)Beijing National Laboratory for Condensed Matter Physics,Shanghai International Collaboration Research Project(19520713900).
文摘Lithium-and manganese-rich(LMR)layered cathode materials hold the great promise in designing the next-generation high energy density lithium ion batteries.However,due to the severe surface phase transformation and structure collapse,stabilizing LMR to suppress capacity fade has been a critical challenge.Here,a bifunctional strategy that integrates the advantages of surface modification and structural design is proposed to address the above issues.A model compound Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)(MNC)with semi-hollow microsphere structure is synthesized,of which the surface is modified by surface-treated layer and graphene/car-bon nanotube dual layers.The unique structure design enabled high tap density(2.1 g cm^(−3))and bidirectional ion diffusion pathways.The dual surface coatings covalent bonded with MNC via C-O-M linkage greatly improves charge transfer efficiency and mitigates electrode degradation.Owing to the synergistic effect,the obtained MNC cathode is highly conformal with durable structure integrity,exhibiting high volumetric energy density(2234 Wh L^(−1))and predominant capacitive behavior.The assembled full cell,with nanograph-ite as the anode,reveals an energy density of 526.5 Wh kg^(−1),good rate performance(70.3%retention at 20 C)and long cycle life(1000 cycles).The strategy presented in this work may shed light on designing other high-performance energy devices.
基金National Natural Science Foundation of China,No.81970698 and No.81900805Peking University People's Hospital Research and Development Funds,No.Project RS2022-03。
文摘BACKGROUND The association between body mass index(BMI)and bone mineral density(BMD)has shown inconsistent results,varying by sex and skeletal site.Despite normal or elevated bone mass,individuals with type 2 diabetes have an increased risk of hip and vertebral fractures.AIM To assess lumbar spine trabecular volumetric BMD(vBMD)across different BMI categories in individuals with and without diabetes.METHODS This cross-sectional study included 966 men over 50 years old and 1001 postmenopausal women from the Pinggu Metabolic Disease Study.The vBMD of lumbar vertebrae 2 through 4 was measured using quantitative computed tomography.Total adipose tissue,subcutaneous adipose tissue(SAT),visceral adipose tissue(VAT),and lumbar skeletal muscle area were also quantified.RESULTS In men with obesity(P=0.038)and overweight(P=0.032),vBMD was significantly higher in the diabetes group compared to non-diabetic men.After adjusting for age and sex,no significant saturation effect between BMI and BMD was found in participants with diabetes or in women without diabetes.However,a BMI threshold of 22.33 kg/m²indicated a saturation point for vBMD in nondiabetic men.Independent predictors of vBMD in men included age(r=-0.387,P<0.001),BMI(r=0.130,P=0.004),and VAT(r=-0.145,P=0.001).For women,significant predictors were age(r=-0.594,P<0.001),BMI(r=0.157,P=0.004),VAT(r=-0.112,P=0.001),and SAT(r=-0.068,P=0.035).CONCLUSION The relationship between BMI and trabecular vBMD differs in individuals with and without diabetes.Overweight and obese men with diabetes exhibit higher vBMD.
基金supported by the National Nature Science Foundations of China (No.21965019)the China Postdoctoral Science Foundation (No.2017M613248)+1 种基金the Natural Science Foundation of Gansu Province (No.1506 RJZA091)the Scientific Research Foundation of the Higher Education Institutions of Gansu Province (No.2015A-037)。
文摘Zinc-ion hybrid super-capacitors are regarded as promising safe energy storage systems,However,the relatively low volumetric energy density has become the main bottlenecks in practical applications of portable electronic devices,In this work,the zinc-ion hybrid super-capacitor with high volumetric energy density and superb cycle stability had been constructed which employing the high-density threedimensional graphene hydrogel as cathode and Zn foil used as anode in 1 mol/L ZnSO4 electrolyte.Benefiting from the abundant ion transport paths and the abundant active sites for graphene hydrogel with high density and porous structure,the zinc-ion hybrid super-capacitor exhibited an extremely high volumetric energy density of 118.42 Wh/L and a superb power density of 24.00 kW/L,as well as an excellent long cycle life(80% retention after 30,000 cycles at 10 A/g),which was superior to the volumetric energy density of the reported zinc-ion hybrid super-capacitors.This device,based on the fast ion adsorption/deso rption on the capacitor-type graphene cathode and reversible Zn^(2+) plating/stripping on the battery-type Zn anode,which will inspire the development of zinc-ion hybrid super-capacitor in miniaturized devices.
基金financial support from the National Natural Science Foundation of China(Nos.22271189,92356301,and 21522105)the Science and Technology Commission of Shanghai Municipality(Nos.21XD1402300,22QC1401500,21JC1401700,and 21DZ2260400)the Double First-Class Initiative Fund of ShanghaiTech University(SYLDX0052022).
文摘In the pursuit of carbon neutrality,hydrogen(H_(2))is often hailed as the ideal fuel for fuel cell vehicles(FCVs)due to its zero-emission nature and high gravimetric energy density.However,its low volumetric density necessitates high-pressure on-board storage(up to 700 bar),which are costly and pose significant safety risks.To cope with these challenges,the U.S.Department of energy(DOE)has set ambitious targets for hydrogen storage systems,aiming for a gravimetric capacity of 6.5 wt%with a volumetric capacity of 50 g L^(-1).Porous crystals,exemplified by metal-organic frameworks(MOFs)[1,2],covalent organic frameworks(COFs),and hydrogen-bonded organic frameworks(HOFs)[3],have shown promise for hydrogen storage at 77 K with delivery at 160 K under significantly lower pressures(≤100 bar).
文摘The scientific article examines the physical and mechanical properties of raw cotton stored in buntings in cotton palaces. Because during the storage of raw cotton in bunts, some of its properties deteriorate, some improvements. Therefore, the mathematical modeling of storage conditions of raw cotton in bunts and the physical and mechanical conditions that occur in it is of great importance. In the developed mathematical model, the main factor influencing the physical and mechanical properties of raw cotton is the change in temperature. Due to the temperature, kinetic and biological processes accumulated in the raw cotton in Bunt, it can spread over a large surface, first in a small-local state, over time with a nonlinear law. As a result, small changes in temperature lead to a qualitative change in physical properties. In determining the law of temperature distribution in the raw cotton in Bunt, Laplace’s differential equation of heat transfer was used. The differential equation of heat transfer in Laplace’s law was replaced by a system of ordinary differential equations by approximation. Conditions are solved in MAPLE-17 program by numerical method. As a result, graphs of temperature changes over time in raw cotton were obtained. In addition, the table shows the changes in density, pressure and mass of cotton, the height of the bun. As the density of the cotton raw material increases from the top layer of the bunt to the bottom layer, an increase in the temperature in it has been observed. This leads to overheating of the bottom layer of cotton and is the main reason for the deterioration of the quality of raw materials.
基金This work was supported by the National Natural Science Foundation of China （No.11374272 and No.11574284） and the Collaborative Innovation Center of Suzhou Nano Science and Technology.
文摘High volumetric power density （VPD） is the basis for the commercial success of micro-tubular solid oxide fuel cells （mtSOFCs）. To find maximal VPD （MVPD） for anode-supported mtSOFC （as-mtSOFC）, the effects of geometric parameters on VPD are analyzed and the anode thickness, tan, and the cathode length, lea, are identified as the key design parameters. Thermo-fluid electrochemical models were built to examine the dependence of the electrical output on the cell parameters. The multiphysics model is validated by reproducing the experimental I-V curves with no adjustable parameters. The optimal lea and the corresponding MVPDs are then determined by the multiphysics model for 20 combinations of rin, the inner tube radius, and tan. And all these optimization are made at 1073.15 K. The results show that： （i） significant performance improvement may be achieved by geometry optimization, （ii） the seemingly high MVPD of 11 and 14 W/cm^3 can be easily realized for as-mtSOFC with single- and double-terminal anode current collection, respectively. Moreover, the variation of the area specific power density with/cac（2 mm, 40 mm） is determined for three representative （tin, tan） combinations. Besides, it is demonstrated that the current output of mtSOFC with proper geometric parameters is comparable to that of planar SOFC.
基金supported by the Ministry of Science and Technology of the People's Republic of China(no.2014CB932402 and 2012AA030303)the National Natural Science Foundation of China(nos.51221264 and 51172242)
文摘LiFePO4/C microspheres with different surface morphologies and porosities were prepared from different carbon sources. The effects of the surface morphology and pore structure of the microspheres on their electrochemical properties and electrode density were investigated. The electrochemical performance and electrode density depended on the morphology and pore structure of the LiFePO4/C microspheres. Open-pore LiFePO4/C microspheres with rough surfaces exhibited good adhesion with current collectors and a high electrode density （2.6g/cm3）. They also exhibited high performance in a half cell and full battery with a high volumetric energy density.
基金financially supported by the National Key R&D Program of China(No.2016YFA0202302)the State Key Program of National Natural Science Foundation of China(Nos.51633007 and 52130303)the National Natural Science Foundation of China(Nos.51773147 and 51973151).
文摘Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand.However,studies on lithium primary batteries are currently focused on the gravimetric energy densities of active materials and rarely account for the volumetric energy requirements of unmanned devices.Herein,CuF_(2)/CF_(x) composites are prepared via planetary ball milling(PBM)to improve the volumetric energy densities of lithium primary batteries using the high mass density of CuF_(2),achieving a maximum volumetric energy density of 4163.40 Wh L^(-1).The CuF_(2)/CF_(x) hybrid cathodes exhibit three distinct discharge plateaus rather than simple combinations of the discharge curves of their components.This phenomenon is caused by charge redistribution and lattice modulation on the contact surfaces of CuF_(2) and CF_(x) during PBM,which change the valence state of Cu and modify the electronic structures of the composites.As a result,CuF_(2)/CF_(x) hybrid cathodes exhibit unique discharge behaviors and improved rate capabilities,delivering a maximum power density of 11.16 kW kg^(-1)(25.56 kW L^(-1)).Therefore,it is a promising strategy to further improve the comprehensive performance of lithium primary batteries through the use of interfacial optimization among different fluoride cathodes.
基金the funding from Natural Science Foundation of China(No.52003163)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515010670)+1 种基金Science and Technology Innovation Commission of Shenzhen(Nos.KQTD20170810105439418 and 20200812112006001)NTUT-SZU Joint Research Program(Nos.2022005 and 2022015)
文摘Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm^(-2)as cathode and anode at 2 mA cm^(-2),and 79.5%and 80%capacity have been preserved at 50 mA cm^(-2).In the meantime,they all showed excellent cycling performance with negligible change after>10000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm^(-2)and 0.352 mW cm^(-3)).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.
基金partially supported by the Natural Science Foundation of Liaoning Province(2023-MS-115)the Large Instrument and Equipment Open Foundation of Dalian University of Technology+1 种基金the National Natural Science Foundation of China(22308261)funding from the Fundamental Research Funds for the Central Universities,conducted at Tongji University。
文摘Electronic textiles hold the merits of high conformability with the human body and natural surrounding,possessing large market demand and wide application foreground in smart wearable and portable devices.However,their further application is largely hindered by the shortage of flexible and stable power sources with multifunctional designability.Herein,a free-standing ZnHCF@CF electrode(ZnHCF grown on carbon nanotube fiber)with good mechanical deformability and high electrochemical performance for aqueous fiber-shaped calcium ion battery(FCIB)is reported.Benefiting from the unique Ca^(2+)/H^(+)co-insertion mechanism,the ZnHCF@CF cathode can exhibit great ion storage capability within a broadened voltage window.By pairing with a polyaniline(PANI)@CF anode,a ZnHCF@CF//PANI@CF FCIB is successfully fabricated,which exhibits a desirable volumetric energy density of 43.2mWh cm^(-3)and maintains superior electrochemical properties under different deformations.Moreover,the high-energy FCIB can be harmoniously integrated with a fiber-shaped strain sensor(FSS)to achieve real-time physiological monitoring on knees during long-running,exhibiting great promise for the practical application of electronic textiles.
基金supported by the National Key Research and Development Program (2016YFB0100200)the National Natural Science Foundation of China (21935006 and 21421001)the Fundamental Research Funds for the Central Universities of China
文摘Although the gravimetric energy density of lithium-sulfur battery is very encouraging,the volumetric energy density still remains a challenge for the practical application.To achieve the high volumetric energy density of battery,much attention should be paid to the sulfur cathode.Herein,we introduce heavy lithium cobalt oxide(LiCoO_(2))nanofibers as sulfur host to enhance the volumetric capacity of cathode,maintaining the high gravimetric capacity simutaneously.With the high tap density of 2.26 g cm^(−3),LiCoO_(2)nanofibers can be used to fabricate a really compact sulfur cathode,with a density and porosity of 0.85 g cm^(−3)and 61.2%,respectively.More importantly,LiCoO2 nanofibers could act as an efficient electrocatalyst for enhancing the redox kinetics of sulfur species,ensuring the cathode electroactivity and alleviating the shuttle effect of polysulfides.Therefore,a balance between compact structure and high electrochemical activity is obtained for the sulfur cathode.At the sulfur loading of 5.1 mg cm^(−2),high volumetric and gravimetric capacities of 724 mA h cm^(−3)cathode and 848 mA h g^(−1)cathode could be achieved based on the cathode volume and weight,respectively.Moreover,with this efficient S/LiCoO_(2)cathode,the lithium corrosion by polysulfides is supressed,leading to a more stable lithium anode.
基金This work was supported by the National Natural Science Foundation of China(51902176)China Postdoctoral Science Foundation(2018M631462)+1 种基金Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341)Shenzhen Municipal Development and Reform Commission and the Development and Reform Commission of Shenzhen Municipality for the development of the“Low-Dimensional Materials and Devices”Discipline.
文摘Potassium ion batteries(PIBs)with high-volumetric energy densities are promising for next-generation low-cost energy storage devices.Metallic bismuth(Bi)with a structure similar to graphite,is a promising anode material for PIBs due to its high theoretical volumetric capacity(3763 mA h cm^−3)and relatively low working potential(−2.93 V vs.standard hydrogen electrode).However,it experiences severe capacity decay caused by a huge volume expansion of Bi when alloying with potassium.This study reports a flexible and free-standing Bi nanosheet(BiNS)/reduced graphene oxide composite membrane with designed porosity close to the expansion ratio of BiNS after charging.The controlled pore structure improves the electron and ion transport during cycling,and strengthens the structural stability of the electrode during potassiation and depotassiation,leading to excellent electrochemical performance for potassium-ion storage.In particular,it delivers a high reversible volumetric capacity of 451 mA h cm^−3 at the current density of 0.5 A g^−1,which is much higher than the previously reported commercial graphite material.
基金sponsored by the National Natural Science Foundation of China(22109010)the National Key R&D Program of China(2021YFC2902905)+3 种基金the Beijing Nova Program,the Chongqing Outstanding Youth Fund(2022NSCQ-JQX3895)the Chongqing Talents Plan for Young Talents(CQYC202005032)the Key Project of Chongqing Technology Innovation and Application Development(2022TIAD-DEX0024)support from the Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Although lithium-rich manganese-based(LRM)cathode materials have high capacity(>250 mAh g^(-1))due to their multi-electron redox mechanisms and offer cost advantages due to their high Mn content,challenges remain before they can achieve commercialization as replacements for lithium cobalt oxides which have high volumetric energy density.Here,we construct a hierarchically structured LRM cathode,featuring primary micro-bricks and abundant exposure of lithium-ion active transport facets({010}planes).Benefiting from these densely packed bricks and rapid lithium-ion active planes,the hierarchical material achieves an optimal compaction density of 3.4 g cm^(-3) and an ultrahigh volumetric energy density of 3431.0 Wh L^(-1),which is the highest performance level to date.Advanced characterizations,including hard X-ray absorption spectra and wide-angle X-ray scattering spectra,combined with density functional theory calculations,demonstrate that the hierarchical material shows a highly reversible charge compensation process and low-strain structural evolution.In addition,when the material has appropriate Li/Ni intermixing,it is not prone to shearing or sliding along the two-dimensional lithium-ion diffusion planes,which promotes robust architectural stability under high-pressure calendering and long-term cycling.This work should promote the development of advanced cathode materials for rechargeable batteries with high volumetric energy density.
