Silicon(Si)and carbon(C)composites hold the promise for replacing the commercial graphite anode,thus increasing the energy density of lithium-ion batteries(LIBs).To mitigate the formation of SiC,this paper reports a m...Silicon(Si)and carbon(C)composites hold the promise for replacing the commercial graphite anode,thus increasing the energy density of lithium-ion batteries(LIBs).To mitigate the formation of SiC,this paper reports a molten salt electrolysis approach to prepare C-Si composite by the electrolysis of C-SiO2 composites.Unlike the conventional way of making a C coating on Si,C-SiO2 composites were prepared by pyrolyzing the low-cost sucrose and silica.The electrochemical deoxidation of the C-SiO2 composites not only produces nanostructured Si inside the C matrix but also introduces voids between the C and Si owing to the volume shrinkage from converting SiO2 to Si.More importantly,the use of Mg ion-containing molten salts precludes the generation of SiC,and the electrolytic Si@C composite anode delivers a capacity of about 1500 mAh g-1 after 100 cycles at a current density of 500 mA g-1.Further,the Si@C‖LiNi0.6Co0.2Mn0.2O2 full cell delivers a high energy density of 608 Wh kg-1.Overall,the molten salt approach provides a one-step electrochemical way to convert oxides@C to metals@C functional materials.展开更多
The chemical composition of vanadium slag significantly affects its element distribution and phase composition,which affect the subsequent calcification roasting process and vanadium recovery.In this work,seven kinds ...The chemical composition of vanadium slag significantly affects its element distribution and phase composition,which affect the subsequent calcification roasting process and vanadium recovery.In this work,seven kinds of vanadium slags derived from different regions in China were used as the raw materials to study the effects of different components on the vanadium slag’s elements distribution,phase composition,calcification roasting,and leaching rate of major elements using scanning electron microscope,X-ray diffraction analysis,and inductively coupled plasma-optical emission spectroscopy.The results show that the spinel phase is wrapped with silicate phase in all vanadium slag samples.The main elements in the spinel phase are Cr,V,and Ti from the interior to the exterior.The size of spinel phase in low chromium vanadium slag is larger than the other vanadium slags with higher chromium contents.The spinel phase of high-calcium and high-phosphorus vanadium slag is more dispersed.The strongest diffraction peak of vanadium spinel phase in the vanadium slag migrates to a higher diffraction angle,and(Fe_(0.6)Cr_(0.4))_(2)O_(3)is formed after calcification roasting as the chromium content increased.A large amount of Ca_(2)SiO_(4)is produced because excess Ca reacts with Si in high-calcium and high-phosphorus vanadium slag.The vanadium leaching rate reaches 88%in some vanadium slags.The chromium leaching rate is less than 5%in all vanadium slags.The silicon leaching rate of high-calcium and high-phosphorus vanadium slag is much higher than that of the other slags.The leaching rate of manganese is higher than 10%,and the leaching rates of iron and titanium are negligible.展开更多
To shorten the time required for the pickling process and to enhance the quality of ferritic stainless steel plates,the effects of oxidants including hydrogen peroxide(H2O2),potassium permanganate(KMnO4),and potas...To shorten the time required for the pickling process and to enhance the quality of ferritic stainless steel plates,the effects of oxidants including hydrogen peroxide(H2O2),potassium permanganate(KMnO4),and potassium chlorate(KClO3)on the pickling behavior in HCl-based electrolyte as well as the surface quality of hot-rolled and blasted 430 stainless steel(430-SS)were studied.Experiments were conducted using mass-loss tests,microstructure analyses,potentiodynamic polarization curves,and electrochemical impedance spectroscopy measurements.The results showed that the addition of oxidants substantially accelerated the pickling process of 430-SS by enhancing the cathodic reaction rate and reducing the charge transfer resistance.In electrolytes comprising 5-8mass% HCl at a temperature of 40-60 ℃ and at the same concentration within the range from 0to 2mass%,H2O2 was demonstrated to be superior to KMnO4 and KClO3in accelerating the pickling process.The surface quality of 430-SS pickled in the presence of H2O2 was better than those of specimens pickled in the presence of KMnO4 and KClO3 when the removal of the oxide layer,intergranular corrosion,and surface roughness were collectively considered.When 1mass% H2O2 was added,the mass loss rate of 430-SS was increased by 629%and no residual oxide layer or intergranular corrosion was observed on the surface of the steel;in addition,the roughness was only 1.7μm.H2O2 was determined to be a better oxidant than KMnO4 and KClO3 when the pickling process,surface quality,solution recycling,and environment protection were considered as a whole.展开更多
The formation of a rust layer on iron and steels surfaces accelerates their degradation and eventually causes material failure.In addition to fabricating a protective layer or using a sacrificial anode, repairing or r...The formation of a rust layer on iron and steels surfaces accelerates their degradation and eventually causes material failure.In addition to fabricating a protective layer or using a sacrificial anode, repairing or removing the rust layer is another way to reduce the corrosion rate and extend the lifespans of iron and steels.Herein, an electrochemical healing approach was employed to repair the rust layer in molten Na_(2)CO_(3)-K_(2)CO_(3).The rusty layers on iron rods and screws were electrochemically converted to iron in only several minutes and a metallic luster appeared.Scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS) analyses showed that the structures of the rust layer after healing were slightly porous and the oxygen content reached a very low level.Thus, high-temperature molten-salt electrolysis may be an effective way to metalize iron rust of various shapes and structures in a short time, and could be used in the repair of cultural relics and even preparing a three-dimensional porous structures for other applications.展开更多
The poor crystallinity and unstable crystal structure of tungsten disulfide(WS2)limit its application in practice.In this paper,a molten salt electrolysis method is proposed to intercalate metal ions into the interlay...The poor crystallinity and unstable crystal structure of tungsten disulfide(WS2)limit its application in practice.In this paper,a molten salt electrolysis method is proposed to intercalate metal ions into the interlayers of layered WS2 to obtain few-layer sheetlike structures.The effect of the molten salt system,applied constant current and electrolysis duration on the exfoliation degree of WS2 bulk has been investigated.The results show that the products electrolyzed in molten LiCl-NaCl-KCl and NaClKCl salts under 25 mA were more transparent and thinner flakes sheets due to the uniform intercalation of Li^+and Na^+with smaller size.The exfoliated WS_(2)was used as an anode material for sodium-ion batteries with a potential of 0.01-2.50 V.In comparison,the WS_(2)-NaCl-25 mA electrode displays a high reversible capacity of 373 mAh·g^(-1)at0.1 A·g^(-1)after cycling for 100 cycles at the same time showing great rate and cycle performance.It also presents a high capacitive ratio of 90.65%at 1.0 mV·s^(-1).The molten salt electrolysis provides a new perspective on the exfoliation of layered material,while demonstrating the great potential of WS2 as an anode material for sodium-ion battery.展开更多
In this study,the gas-solid flow process in the blast furnace raceway is numerically simulated using coupled computational fluid dynamics and the discrete element method(CFD-DEM).The coke reaction kinetics data are im...In this study,the gas-solid flow process in the blast furnace raceway is numerically simulated using coupled computational fluid dynamics and the discrete element method(CFD-DEM).The coke reaction kinetics data are imported into the DEM model to reproduce the consumption process of each coke particle.The effects of inlet gas velocity and angle on the morphology of the raceway,coke consumption rate,coke bed temperature,and particle size distribution in the blast process are systematically investigated and analyzed.The results show that the consumption of coke particles promotes the formation of raceways during the blast process.At the same time,a coke mixture layer is produced at the edge of the raceway.The higher the inlet gas velocity,the thicker the coke mixture layer in the middle and upper parts of the raceway region,and the larger the proportion of small particles in the coke mixture layer.The effect of the inlet gas angle on the raceway region is less than the inlet gas velocity.However,with the increase in the inlet gas angle,the high-temperature region of the coke bed extends downward gradually,which is conducive to activating the hearth.展开更多
Integrating electrochemical reduction of CO_(2)and electrochemical oxidation to recycle degraded superalloys is a promising solution to ease resource scarcity and safeguard environmental sustainability.Herein,we propo...Integrating electrochemical reduction of CO_(2)and electrochemical oxidation to recycle degraded superalloys is a promising solution to ease resource scarcity and safeguard environmental sustainability.Herein,we propose an electrochemical technique for the conversion of bulk superalloy scraps and CO_(2)into oxide powder at the anode and solid carbon at the cathode,respectively.In particular,a borax-modifi ed CaCl_(2)-based molten salt electrolyte is used for enhancing the electrochemical oxidation of superalloy scraps.At a temperature of 700℃and a voltage of 2.8 V,90.55 wt.%of alloy scraps were oxidized in a molten CaCl_(2)–NaCl–CaCO_(3)–Na_(2)B_(4)O_(7)with an acid–base ratio(K_(a/b))of 1.The synergy of Cl−and B_(4)O_(7)2−of electrolyte prevents the passivation of the alloy anode and enables continuous oxidation.Furthermore,the Ni and Co in the anode products are recovered by sulfation roasting with recovery efficiencies of 85.58%and 95.27%for Ni and Co,respectively.Overall,modulating the alkalinity of the electrolyte for enhancing oxidation/pulverization of alloy scrap anode provides new insight into electrochemically recovering superalloy scraps.展开更多
Alloy-type metals/alloys hold the promise of increasing the energy density of metal-ion batteries(MIBs)because of their theoretical high gravimetrical capacities.Semimetals and semimetal-analogs are typical alloy-type...Alloy-type metals/alloys hold the promise of increasing the energy density of metal-ion batteries(MIBs)because of their theoretical high gravimetrical capacities.Semimetals and semimetal-analogs are typical alloy-type anodes.Currently,the large-scale extraction of semimetals(Si,Ge)and semimetal-analogs(Sb,Bi,Sn)by traditional metallurgical routes highly relies on using reducing agents(e.g.,carbon,hydrogen,reactive metals),which consumes a large number of fossil fuels and produces greenhouse gas emissions.In addition,the common metallurgical methods for extracting semimetals involve relatively high operating temperatures and therefore produce bulk metal ingots solidified from the liquid metals.However,the commonly used electrode materials in batteries are fine powders.Thus,directly producing semimetal powders would be more energy efficient.In addition,semimetals are good candidates to host alkali/alkaline-earth ions through the alloying process because the electronegativity of semimetals is high.Therefore,preparing semimetal powders via an environment-sound manner is of great interest to provide sustainable anode materials for MIBs while reducing the ecological footprint.Low-cost and high-output capacity anode powder materials,as well as straightforward and environmental-benign synthetic methods,play key roles in enabling the energy conversion and storage technologies for real applications of MIBs.Electrochemical technologies offer new strategies to extract semimetals using electrons as the reducing agent that comes from renewable energies.Besides,the morphologies and structures of the electrolytic products can be rationally tailored by tuning the electrode potentials,electrolytes,and operating temperatures.In this regard,using the one-step green electrochemical method to prepare high-capacity and cheaper alloy-type metalloids for MIB anodes can fulfill the requirements for developing MIBs.This review critically overviews recent developments and advances in the electrochemical extraction of semimetals(Si,Ge)and semimetal-analogs(Sb,Bi,Sn)for MIBs,including basic electrochemical principles,thermodynamic analysis,manufacture strategies and applications in lithium-ion batteries(LIBs),sodium-ion batteries(SIBs),potassium-ion batteries(PIBs),magnesium-ion batteries(Mg-ion batteries),and liquid metal batteries(LMBs).It also presents challenges and prospects of employing electrochemical approaches for preparing alloy-type anode materials directly from inexpensive ore-originated feedstocks.展开更多
基金the financial support from the National Training Program of Innovation and Entrepreneurship for Undergraduates(201810145075)Fundamental Research Funds for the Central Universities(N172505002)+2 种基金NSFC(51704060)National Thousand Youth Talent Program of Chinathe 111 Project(B16009)
文摘Silicon(Si)and carbon(C)composites hold the promise for replacing the commercial graphite anode,thus increasing the energy density of lithium-ion batteries(LIBs).To mitigate the formation of SiC,this paper reports a molten salt electrolysis approach to prepare C-Si composite by the electrolysis of C-SiO2 composites.Unlike the conventional way of making a C coating on Si,C-SiO2 composites were prepared by pyrolyzing the low-cost sucrose and silica.The electrochemical deoxidation of the C-SiO2 composites not only produces nanostructured Si inside the C matrix but also introduces voids between the C and Si owing to the volume shrinkage from converting SiO2 to Si.More importantly,the use of Mg ion-containing molten salts precludes the generation of SiC,and the electrolytic Si@C composite anode delivers a capacity of about 1500 mAh g-1 after 100 cycles at a current density of 500 mA g-1.Further,the Si@C‖LiNi0.6Co0.2Mn0.2O2 full cell delivers a high energy density of 608 Wh kg-1.Overall,the molten salt approach provides a one-step electrochemical way to convert oxides@C to metals@C functional materials.
基金financially supported by the National Natural Science Foundation of China (No. 51874077)the Opening Foundation of State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, China (No. 2019P4FZG00A)
文摘The chemical composition of vanadium slag significantly affects its element distribution and phase composition,which affect the subsequent calcification roasting process and vanadium recovery.In this work,seven kinds of vanadium slags derived from different regions in China were used as the raw materials to study the effects of different components on the vanadium slag’s elements distribution,phase composition,calcification roasting,and leaching rate of major elements using scanning electron microscope,X-ray diffraction analysis,and inductively coupled plasma-optical emission spectroscopy.The results show that the spinel phase is wrapped with silicate phase in all vanadium slag samples.The main elements in the spinel phase are Cr,V,and Ti from the interior to the exterior.The size of spinel phase in low chromium vanadium slag is larger than the other vanadium slags with higher chromium contents.The spinel phase of high-calcium and high-phosphorus vanadium slag is more dispersed.The strongest diffraction peak of vanadium spinel phase in the vanadium slag migrates to a higher diffraction angle,and(Fe_(0.6)Cr_(0.4))_(2)O_(3)is formed after calcification roasting as the chromium content increased.A large amount of Ca_(2)SiO_(4)is produced because excess Ca reacts with Si in high-calcium and high-phosphorus vanadium slag.The vanadium leaching rate reaches 88%in some vanadium slags.The chromium leaching rate is less than 5%in all vanadium slags.The silicon leaching rate of high-calcium and high-phosphorus vanadium slag is much higher than that of the other slags.The leaching rate of manganese is higher than 10%,and the leaching rates of iron and titanium are negligible.
基金Item Sponsored by Liaoning Province Programs for Science and Technology Development of China(2012221013)
文摘To shorten the time required for the pickling process and to enhance the quality of ferritic stainless steel plates,the effects of oxidants including hydrogen peroxide(H2O2),potassium permanganate(KMnO4),and potassium chlorate(KClO3)on the pickling behavior in HCl-based electrolyte as well as the surface quality of hot-rolled and blasted 430 stainless steel(430-SS)were studied.Experiments were conducted using mass-loss tests,microstructure analyses,potentiodynamic polarization curves,and electrochemical impedance spectroscopy measurements.The results showed that the addition of oxidants substantially accelerated the pickling process of 430-SS by enhancing the cathodic reaction rate and reducing the charge transfer resistance.In electrolytes comprising 5-8mass% HCl at a temperature of 40-60 ℃ and at the same concentration within the range from 0to 2mass%,H2O2 was demonstrated to be superior to KMnO4 and KClO3in accelerating the pickling process.The surface quality of 430-SS pickled in the presence of H2O2 was better than those of specimens pickled in the presence of KMnO4 and KClO3 when the removal of the oxide layer,intergranular corrosion,and surface roughness were collectively considered.When 1mass% H2O2 was added,the mass loss rate of 430-SS was increased by 629%and no residual oxide layer or intergranular corrosion was observed on the surface of the steel;in addition,the roughness was only 1.7μm.H2O2 was determined to be a better oxidant than KMnO4 and KClO3 when the pickling process,surface quality,solution recycling,and environment protection were considered as a whole.
基金Projects(51774079,51674075)supported by the National Natural Science Foundation of ChinaProject(N182508026)supported by the Fundamental Research Funds for the Central Universities,China。
基金financially supported by the Fundamental Research Funds for the Central Universities (No.N172505002)the National Natural Science Foundation of China (No.51704060)+1 种基金the National Thousand Youth Talent Program of Chinathe 111 Project (No.B16009)。
文摘The formation of a rust layer on iron and steels surfaces accelerates their degradation and eventually causes material failure.In addition to fabricating a protective layer or using a sacrificial anode, repairing or removing the rust layer is another way to reduce the corrosion rate and extend the lifespans of iron and steels.Herein, an electrochemical healing approach was employed to repair the rust layer in molten Na_(2)CO_(3)-K_(2)CO_(3).The rusty layers on iron rods and screws were electrochemically converted to iron in only several minutes and a metallic luster appeared.Scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS) analyses showed that the structures of the rust layer after healing were slightly porous and the oxygen content reached a very low level.Thus, high-temperature molten-salt electrolysis may be an effective way to metalize iron rust of various shapes and structures in a short time, and could be used in the repair of cultural relics and even preparing a three-dimensional porous structures for other applications.
基金financially supported by the Fundamental Research Funds for the Central Universities(Nos.N2025034 and N2025035)Xingliao Project(No.XLYC1807042)the Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities(No.B16009)。
文摘The poor crystallinity and unstable crystal structure of tungsten disulfide(WS2)limit its application in practice.In this paper,a molten salt electrolysis method is proposed to intercalate metal ions into the interlayers of layered WS2 to obtain few-layer sheetlike structures.The effect of the molten salt system,applied constant current and electrolysis duration on the exfoliation degree of WS2 bulk has been investigated.The results show that the products electrolyzed in molten LiCl-NaCl-KCl and NaClKCl salts under 25 mA were more transparent and thinner flakes sheets due to the uniform intercalation of Li^+and Na^+with smaller size.The exfoliated WS_(2)was used as an anode material for sodium-ion batteries with a potential of 0.01-2.50 V.In comparison,the WS_(2)-NaCl-25 mA electrode displays a high reversible capacity of 373 mAh·g^(-1)at0.1 A·g^(-1)after cycling for 100 cycles at the same time showing great rate and cycle performance.It also presents a high capacitive ratio of 90.65%at 1.0 mV·s^(-1).The molten salt electrolysis provides a new perspective on the exfoliation of layered material,while demonstrating the great potential of WS2 as an anode material for sodium-ion battery.
基金support by the National Natural Science Foundation of China(grant Nos.51874171,52074150,51974154).
文摘In this study,the gas-solid flow process in the blast furnace raceway is numerically simulated using coupled computational fluid dynamics and the discrete element method(CFD-DEM).The coke reaction kinetics data are imported into the DEM model to reproduce the consumption process of each coke particle.The effects of inlet gas velocity and angle on the morphology of the raceway,coke consumption rate,coke bed temperature,and particle size distribution in the blast process are systematically investigated and analyzed.The results show that the consumption of coke particles promotes the formation of raceways during the blast process.At the same time,a coke mixture layer is produced at the edge of the raceway.The higher the inlet gas velocity,the thicker the coke mixture layer in the middle and upper parts of the raceway region,and the larger the proportion of small particles in the coke mixture layer.The effect of the inlet gas angle on the raceway region is less than the inlet gas velocity.However,with the increase in the inlet gas angle,the high-temperature region of the coke bed extends downward gradually,which is conducive to activating the hearth.
基金support from Fundamental Research Funds for the Central Universities(N2025034)Xingliao Project(XLYC1807042)the 111 Project(B16009).
文摘Integrating electrochemical reduction of CO_(2)and electrochemical oxidation to recycle degraded superalloys is a promising solution to ease resource scarcity and safeguard environmental sustainability.Herein,we propose an electrochemical technique for the conversion of bulk superalloy scraps and CO_(2)into oxide powder at the anode and solid carbon at the cathode,respectively.In particular,a borax-modifi ed CaCl_(2)-based molten salt electrolyte is used for enhancing the electrochemical oxidation of superalloy scraps.At a temperature of 700℃and a voltage of 2.8 V,90.55 wt.%of alloy scraps were oxidized in a molten CaCl_(2)–NaCl–CaCO_(3)–Na_(2)B_(4)O_(7)with an acid–base ratio(K_(a/b))of 1.The synergy of Cl−and B_(4)O_(7)2−of electrolyte prevents the passivation of the alloy anode and enables continuous oxidation.Furthermore,the Ni and Co in the anode products are recovered by sulfation roasting with recovery efficiencies of 85.58%and 95.27%for Ni and Co,respectively.Overall,modulating the alkalinity of the electrolyte for enhancing oxidation/pulverization of alloy scrap anode provides new insight into electrochemically recovering superalloy scraps.
基金the National Natural Science Foundation of China(No.51704060)the Fundamental Research Funds for the Central Universities(No.N172505002)the Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities(No.B16009)。
文摘Alloy-type metals/alloys hold the promise of increasing the energy density of metal-ion batteries(MIBs)because of their theoretical high gravimetrical capacities.Semimetals and semimetal-analogs are typical alloy-type anodes.Currently,the large-scale extraction of semimetals(Si,Ge)and semimetal-analogs(Sb,Bi,Sn)by traditional metallurgical routes highly relies on using reducing agents(e.g.,carbon,hydrogen,reactive metals),which consumes a large number of fossil fuels and produces greenhouse gas emissions.In addition,the common metallurgical methods for extracting semimetals involve relatively high operating temperatures and therefore produce bulk metal ingots solidified from the liquid metals.However,the commonly used electrode materials in batteries are fine powders.Thus,directly producing semimetal powders would be more energy efficient.In addition,semimetals are good candidates to host alkali/alkaline-earth ions through the alloying process because the electronegativity of semimetals is high.Therefore,preparing semimetal powders via an environment-sound manner is of great interest to provide sustainable anode materials for MIBs while reducing the ecological footprint.Low-cost and high-output capacity anode powder materials,as well as straightforward and environmental-benign synthetic methods,play key roles in enabling the energy conversion and storage technologies for real applications of MIBs.Electrochemical technologies offer new strategies to extract semimetals using electrons as the reducing agent that comes from renewable energies.Besides,the morphologies and structures of the electrolytic products can be rationally tailored by tuning the electrode potentials,electrolytes,and operating temperatures.In this regard,using the one-step green electrochemical method to prepare high-capacity and cheaper alloy-type metalloids for MIB anodes can fulfill the requirements for developing MIBs.This review critically overviews recent developments and advances in the electrochemical extraction of semimetals(Si,Ge)and semimetal-analogs(Sb,Bi,Sn)for MIBs,including basic electrochemical principles,thermodynamic analysis,manufacture strategies and applications in lithium-ion batteries(LIBs),sodium-ion batteries(SIBs),potassium-ion batteries(PIBs),magnesium-ion batteries(Mg-ion batteries),and liquid metal batteries(LMBs).It also presents challenges and prospects of employing electrochemical approaches for preparing alloy-type anode materials directly from inexpensive ore-originated feedstocks.