Metallic lithium(Li)is considered the“Holy Grail”anode material for the nextgeneration of Li batteries with high energy density owing to the extraordinary theoretical specific capacity and the lowest negative electr...Metallic lithium(Li)is considered the“Holy Grail”anode material for the nextgeneration of Li batteries with high energy density owing to the extraordinary theoretical specific capacity and the lowest negative electrochemical potential.However,owing to inhomogeneous Li-ion flux,Li anodes undergo uncontrollable Li deposition,leading to limited power output and practical applications.Carbon materials and their composites with controllable structures and properties have received extensive attention to guide the homogeneous growth of Li to achieve high-performance Li anodes.In this review,the correlation between the behavior of Li anode and the properties of carbon materials is proposed.Subsequently,we review emerging strategies for rationally designing high-performance Li anodes with carbon materials,including interface engineering(stabilizing solid electrolyte interphase layer and other functionalized interfacial layer)and architecture design of host carbon(constructing three-dimension structure,preparing hollow structure,introducing lithiophilic sites,optimizing geometric effects,and compositing with Li).Based on the insights,some prospects on critical challenges and possible future research directions in this field are concluded.It is anticipated that further innovative works on the fundamental chemistry and theoretical research of Li anodes are needed.展开更多
Tooth germ injury can lead to abnormal tooth development and even tooth loss,affecting various aspects of the stomatognathic system including form,function,and appearance.However,the research about tooth germ injury m...Tooth germ injury can lead to abnormal tooth development and even tooth loss,affecting various aspects of the stomatognathic system including form,function,and appearance.However,the research about tooth germ injury model on cellular and molecule mechanism of tooth germ repair is still very limited.Therefore,it is of great importance for the prevention and treatment of tooth germ injury to study the important mechanism of tooth germ repair by a tooth germ injury model.Here,we constructed a Tg(dlx2b:Dendra2-NTR)transgenic line that labeled tooth germ specifically.Taking advantage of the NTR/Mtz system,the dlx2b+tooth germ cells were depleted by Mtz effectively.The process of tooth germ repair was evaluated by antibody staining,in situ hybridization,Ed U staining and alizarin red staining.The severely injured tooth germ was repaired in several days after Mtz treatment was stopped.In the early stage of tooth germ repair,the expression of phosphorylated 4E-BP1 was increased,indicating that mTORC1 is activated.Inhibition of mTORC1 signaling in vitro or knockdown of mTORC1 signaling in vivo could inhibit the repair of injured tooth germ.Normally,mouse incisors were repaired after damage,but inhibition/promotion of mTORC1 signaling inhibited/promoted this repair progress.Overall,we are the first to construct a stable and repeatable repair model of severe tooth germ injury,and our results reveal that mTORC1 signaling plays a crucial role during tooth germ repair,providing a potential target for clinical treatment of tooth germ injury.展开更多
Rechargeable aluminum batteries(RABs)are attractive cadidates for next-generation energy storage and conversion,due to the low cost and high safety of Al resources,and high capacity of metal Al based on the three-elec...Rechargeable aluminum batteries(RABs)are attractive cadidates for next-generation energy storage and conversion,due to the low cost and high safety of Al resources,and high capacity of metal Al based on the three-electrons reaction mechanism.However,the development of RABs is greatly limited,because of the lack of advanced cathode materials,and their complicated and unclear reaction mechanisms.Exploring the novel nanostructured transition metal and carbon composites is an effective route for obtaining ideal cathode materials.In this work,we synthesize porous CoSnO_(3)/C nanocubes with oxygen vacancies for utilizing as cathodes in RABs for the first time.The intrinsic structure stability of the mixed metal cations and carbon coating can improve the cycling performance of cathodes by regulating the internal strains of the electrodes during volume expansion.The nanocubes with porous structures contribute to fast mass transportation which improves the rate capability.In addition to this,abundant oxygen vacancies promote the adsorption affinity of cathodes,which improves storage capacity.As a result,the CoSnO_(3)/C cathodes display an excellent reversible capacity of 292.1 mAh g^(-1) at 0.1 A g^(-1),a good rate performance with 109 mAh g^(-1) that is maintained even at 1 A g^(-1) and the provided stable cycling behavior for 500 cycles.Besides,a mechanism of intercalation of Al^(3+)within CoSnO_(3)/C cathode is proposed for the electrochemical process.Overall,this work provides a step toward the development of advanced cathode materials for RABs by engineering novel nanostructured mixed transition-metal oxides with carbon composite and proposes novel insights into chemistry for RABs.展开更多
Developing effective strategies to improve the initial Coulombic efficiency(ICE)and cycling stability of hard carbon(HC)anodes for sodium-ion batteries is the key to promoting the commercial application of HC.In this ...Developing effective strategies to improve the initial Coulombic efficiency(ICE)and cycling stability of hard carbon(HC)anodes for sodium-ion batteries is the key to promoting the commercial application of HC.In this paper,homotype heterojunctions are designed on HC to induce the generation of stable solid electrolyte interfaces,which can effectively increase the ICE of HC from 64.7%to 81.1%.The results show that using a simple surface engineering strategy to construct a homotypic amorphous Al_(2)O_(3) layer on the HC could shield the active sites,and further inhibit electrolyte decomposition and side effects occurrence.Particularly,due to the suppression of continuous decomposition of NaPF 6 in ester-based electrolytes,the accumulation of NaF could be reduced,leading to the formation of thinner and denser solid electrolyte interface films and a decrease in the interface resistance.The HC anode can not only improve the ICE but elevate its sodium storage performance based on this homotype heterojunction composed of HC and Al_(2)O_(3).The optimized HC anode exhibits an outstanding reversible capacity of 321.5mAhg^(−1) at 50mAg^(−1).The cycling stability is also improved effectively,and the capacity retention rate is 86.9%after 2000 cycles at 1Ag^(−1) while that of the untreated HC is only 52.6%.More importantly,the improved sodium storage behaviors are explained by electrochemical kinetic analysis.展开更多
Grain growth, mechanical properties, and fracture mechanism of nickel-based GH4099 superalloy are investigated using heat treatments, tensile tests, optical microscopy (OM), and scanning electron microscopy (SEM) with...Grain growth, mechanical properties, and fracture mechanism of nickel-based GH4099 superalloy are investigated using heat treatments, tensile tests, optical microscopy (OM), and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The OM observation shows that the matrix grains (γ-grains) undergo an apparent growth during the solution treatment. The grain size diameter increases from 100 to 174 μm when the solution temperature rises from 1100℃ to 1160℃ for 30 min. When the holding time increases from 15 to 60 min at 1140℃, the grain size diameter increases from 140 to 176 μm, indicating that the γ-grain growth is more sensitive to temperature than time. Standard deviation, <em>S</em><sub>v</sub>, and the grain size distribution are utilized to characterize the microstructural uniformity. To predict the grain size more accurately, we develop the grain growth kinetics and find that the growth index is close to 5. The yield strength (<em>R</em><sub>p0.2</sub>), tensile strength (<em>R</em><sub>m</sub>), and ductility (<em>A</em><sub>f</sub>) are also measured. It is found that the effect decreases in the order cooling rate, solution temperature, time. <em>R</em><sub>p0.2</sub> reduces by 47% with the increase in the cooling rate from 1℃ to 8000℃/min, while both strength and ductility exhibit little changes with time. The SEM results show that the fracture surfaces have typical mixed brittle and ductile characteristics when specimens are subjected to water quenching and air cooling. However, a complete brittle fracture occurs under furnace cooling conditions. The EDS analysis indicates that the brittle γ' (Ni<sub>3</sub>Ti) phase precipitates around the γ-grain boundary during the slow cooling process, which is the main factor yielding the complete brittle fracture. Finally, the optimal solution treatment scheme for the GH4099 superalloy is proposed—a temperature of 1140℃ for 30 min followed by air cooling.展开更多
Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impede...Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impedes the commercial application. The initial nucleation and low Li ions diffusion rate in the electrolyte/electrode interface dominate the deposition behavior. Therefore, a uniform and flexible interface is urgently needed. Here, a facile method is proposed to prepare a thin and porous LiF-rich layer (TPL) by the in-situ reaction of small amount of ammonium hydrogen difluoride (NH4HF2) and Li metal. The deposition morphology on Li metal anode with LiF layer is significantly flat and homogeneous owning to low lateral diffusion barrier on LiF crystals and the porous structure of TPL film. Additionally, the symmetrical cells made with such TPL Li anodes show significantly stable cycling over 100 cycles at high current density of 6 mA/cm^2. The TPL Li|LiFePO4 full cells keep over 99% capacity retention after 100 cycles at 2.0 C. This approach serves as a facile and controllable way of adjusting the protective layer on Li metal.展开更多
In this work, we report a facile route for the synthesis of Li3V2(PO4)3/C cathode material via freezedrying and then calcination. The effect of calcination temperature on the electrochemical properties of the Li3V2(PO...In this work, we report a facile route for the synthesis of Li3V2(PO4)3/C cathode material via freezedrying and then calcination. The effect of calcination temperature on the electrochemical properties of the Li3V2(PO4)3/C is also investigated. When used as a lithium-ion battery cathode, the optimized Li3V2(PO4)3/C (LVP-800) through calcination at 800 ℃ exhibits a high initial charge and discharge capacity. The excellent electrochemical performance of LVP-800 is attributed to the good crystallinity and uniform morphology of the electrode material. In addition, the residual carbon can also improve the conductivity and buffer the volume expansion during the Li-ion extraction/reinsertion. Meanwhile, charge compensation also plays an important role in excellent electrochemical performance.展开更多
To meet the requirements of electronic vehicles(EVs) and hybrid electric vehicles(HEVs),the high energy density Li Ni_(0.8) Co_(0.15) Al_(0.05) O_2(NCA) cathode and Si–C anode have attracted more attention.Here we re...To meet the requirements of electronic vehicles(EVs) and hybrid electric vehicles(HEVs),the high energy density Li Ni_(0.8) Co_(0.15) Al_(0.05) O_2(NCA) cathode and Si–C anode have attracted more attention.Here we report the thermal behaviors of NCA/Si–C pouch cell during the charge/discharge processes at different current densities.The total heat generations are derived from the surface temperature change during electrochemical Li+insertion/extraction in adiabatic surrounding.The reversible heat is determined by the entropic coefficients,which are related with open-circuit voltage at different temperatures; while the irreversible heat is determined by the internal resistance,which can be obtained via V–I characteristic,electrochemical impedance spectroscopy and hybrid pulse power characterization(HPPC).During the electrochemical process,the reversible heat contributes less than 10% to total heat generation; and the heat generated in charge process is less than that in discharge process.The results of thermal behaviors analyses are conducive to understanding the safety management and paving the way for building a reliable thermal model of high energy density lithium ion battery.展开更多
The dependence on portable devices and electrical vehicles has triggered the awareness on the energy storage systems with ever-growing energy density.Lithium metal batteries(LMBs)has revived and attracted considerable...The dependence on portable devices and electrical vehicles has triggered the awareness on the energy storage systems with ever-growing energy density.Lithium metal batteries(LMBs)has revived and attracted considerable attention due to its high volumetric(2046 m Ah cm-3),gravimetric specific capacity(3862 m Ah g^(-1))and the lowest reduction potential(-3.04 V vs.SHE.).However,during the electrochemical process of lithium anode,the growth of lithium dendrite constitutes the biggest stumbling block on the road to LMBs application.The undesirable dendrite not only limit the Coulombic efficiency(CE)of LMBs,but also cause thermal runaway and other safety issues due to short-circuits.Understanding the mechanisms of lithium nucleation and dendrite growth provides insights to solve these problems.Herein,we summarize the electrochemical models that inherently describe the lithium nucleation and dendrite growth,such as the thermodynamic,electrodeposition kinetics,internal stress,and interface transmission models.Essential parameters of temperature,current density,internal stress and interfacial Li+flux are focused.To improve the LMBs performance,state-of-the-art optimization procedures have been developed and systematically illustrated with the intrinsic regulation principles for better lithium anode stability,including electrolyte optimization,artificial interface layers,threedimensional hosts,external field,etc.Towards practical applications of LMBs,the current development of pouch cell LMBs have been further introduced with different assembly systems and fading mechanism.However,challenges and obstacles still exist for the development of LMBs,such as in-depth understanding and in-situ observation of dendrite growth,the surface protection under extreme condition and the self-healing of solid electrolyte interface.展开更多
Li4Ti5012 (LTO) with rich R-TiO2 (17.06, 23.69, and 34.42 wt%), namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate (TBT) as the precursor. Rietveld refinement o...Li4Ti5012 (LTO) with rich R-TiO2 (17.06, 23.69, and 34.42 wt%), namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate (TBT) as the precursor. Rietveld refinement of X-ray diffraction (XRD) results show that the proportion of Li occupying 16d sites is extraordinary low and the lattice constants of LTO and R-TiO2 change with the ritanium dioxide content. EIS measurements showed that with in creasing R-TiO2 content, both its charge transfer impedance (Rct) and lithium ion diffusion coefficient (DLi) decreased. The changes of Rct and DLi caused by the increase of titanium dioxide content have synergic-antagonistic effects on the rate and cycle properties of Li4Ti5012. The rate performance is positively related to DLi, while the cycle property is negatively correlated with Rct, indicati ng that the rate performs nee is mainly related to DLi, while Rct more significantly affects the cycle performance. LTO-RT-17.06% exhibited excellent rate properties, especially under a high current density (5.0 C, 132.5 mAh/g) and LTO-RT-34.42% showed superior long-term cycle performance (0.012% capacity loss per cycle) compared to that of LTO-RT-17.06% and LTO-RT-23.69%.展开更多
The past decade has witnessed the germination of rechargeable aluminum batteries(RABs)with the colossal potential to enact as a device for the large scale energy storage and conversion.The Majority of investigations a...The past decade has witnessed the germination of rechargeable aluminum batteries(RABs)with the colossal potential to enact as a device for the large scale energy storage and conversion.The Majority of investigations are dedicated to the exploration of suitable cathode materials,while less is known about the electrode/electrolyte interfaces that determine the electrochemistry of batteries.In this perspective,we will highlight the significance of electrode/electrolyte interface for RABs,in overall kinetics and capacity retention.Emphasis will be laid on the complicated yet basic understandings of the phenomena at the interfaces,including the dendrite growth,surface Al2O3 and solid–electrolyte-interphase(SEI).And we will summarize the reported practice in effort to build better electrode/electrolyte interfaces in RAB.In the end,outlook regarding to the challenges,opportunities and directions is presented.展开更多
Rechargeable aluminum ion battery(AIB) with high theoretical specific capacity, abundant elements and low cost engages considerable attention as a promising next generation energy storage and conversion system. Nevert...Rechargeable aluminum ion battery(AIB) with high theoretical specific capacity, abundant elements and low cost engages considerable attention as a promising next generation energy storage and conversion system. Nevertheless, to date, one of the major barriers to pursuit better AIB is the limited applicable cathode materials with the ability to store aluminum highly reversibly. Herein, a highly reversible AIB is proposed using mesoporous TiO2 microparticles(M-TiO2) as the cathode material. The improved performance of Ti O2/Al battery is ascribed to the high ionic conductivity and material stability, which is caused by the stable architecture with a mesoporous microstructure and no random aggregation of secondary particles. In addition, we conducted detailed characterization to gain deeper understanding of the Al^(3+) storage mechanism in anatase Ti O2 for AIB. Our findings demonstrate clearly that Al^(3+)can be reversibly stored in anatase TiO2 by intercalation reactions based on ionic liquid electrolyte. Especially, DFT calculations were used to investigate the accurate insertion sites of aluminum ions in M-Ti O2 and the volume changes of M-TiO2 cells during discharging. As for the controversial side reactions in AIBs, in this work, by normalized calculation, we confirm that M-Ti O2 alone participate in the redox reaction. Moreover, cyclic voltammetry(CV) test was performed to investigate the pseudocapacitive behavior.展开更多
A great deal of attention has been paid on developing plant-derived hard carbon(HC)materials as anodes for sodium-ion batteries(SIBs).So far,the regulation of HC has been handicapped by the well-known ambiguity of Na^...A great deal of attention has been paid on developing plant-derived hard carbon(HC)materials as anodes for sodium-ion batteries(SIBs).So far,the regulation of HC has been handicapped by the well-known ambiguity of Na^(+)storage mechanism,which fails to differentiate the Na^(+)adsorption and Na^(+)insertion,and their relationship with the size of d-interlayer spacing and structural porosity.Herein,bagassederived HC materials have been synthesized through a combination of pyrolysis treatment and microwave activation.The combined protocol has enabled to synergistically control the d-interlayer spacing and porosity.Specifically,the microwave activation has created slit pores into HC and these pores allow for an enhanced Na^(+)adsorption with an increased sloping capacity,establishing a strong correlation between the porosity and sloping capacity.Meanwhile,the pyrolysis treatment promotes the graphitization and it contributes to an intensified Na^(+)insertion with an increased plateau capacity,proving that the plateau capacity is largely contributed by the Na^(+)insertion between interlayers.Therefore,the structural regulation of bagasse-derived HC has provided a proof on positively explaining the Na^(+)storage with HC materials.The structural changes in the pore size distribution,specific surface area,d-interlayer spacing,and the electrochemical properties have been comprehensively characterized,all supporting our understanding of Na^(+)storage mechanism.As a result,the HC sample with an optimized d-interlayer spacing and porosity has delivered an improved reversible capacity of 323.6 m Ah g^(-1) at 50 m A g^(-1).This work provides an understanding of Na^(+)storage mechanism and insights on enhancing the sloping/plateau capacity by rationally regulating the graphitization and porosity of HC materials for advanced SIBs.展开更多
Gas drainage is carried out based on output from each coal bed throughout commingling production of coalbed methane(CBM).A reasonable drainage process should therefore initially guarantee main coal bed production and ...Gas drainage is carried out based on output from each coal bed throughout commingling production of coalbed methane(CBM).A reasonable drainage process should therefore initially guarantee main coal bed production and then enhance gas output from other beds.Permanent damage can result if this is not the case,especially with regard to fracture development in the main gas-producing coal bed and can greatly reduce single well output.Current theoretical models and measuring devices are inapplicable to commingled CBM drainage,however,and so large errors in predictive models cannot always be avoided.The most effective currently available method involves directly measuring gas output from each coal bed as well as determining the dominant gas-producing unit.A dynamic evaluation technique for gas output from each coal bed during commingling CBM production is therefore proposed in this study.This technique comprises a downhole measurement system combined with a theoretical calculation model.Gas output parameters(i.e.,gas-phase flow rate,temperature,pressure)are measured in this approach via a downhole measurement system;substituting these parameters into a deduced theoretical calculation model then means that gas output from each seam can be calculated to determine the main gas-producing unit.Trends in gas output from a single well or each seam can therefore be predicted.The laboratory and field test results presented here demonstrate that calculation errors in CBM outputs can be controlled within a margin of 15%and therefore conform with field use requirements.展开更多
Multivalent metal-sulfur(M-S,where M=Mg,Al,Ca,Zn,Fe,etc.)batteries offer unique opportunities to achieve high specific capacity,elemental abundancy and cost-effectiveness beyond lithium-ion batteries(LIBs).However,the...Multivalent metal-sulfur(M-S,where M=Mg,Al,Ca,Zn,Fe,etc.)batteries offer unique opportunities to achieve high specific capacity,elemental abundancy and cost-effectiveness beyond lithium-ion batteries(LIBs).However,the slow diffusion of multivalent-metal ions and the shuttle of soluble polysulfide result in impoverished reversible capacity and limited cycle performance of M-S(Mg-S,Al-S,Ca-S,Zn-S,Fe-S,etc.)batteries.It is a necessity to optimize the electrochemical performance,while deepening the understanding of the unique electrochemical reaction mechanism,such as the intrinsic multi-electron reaction process,polysulfides dissoluti on and the in stability of metal an odes.To solve these problems,we have summarized the state-of-the-art progress of current M-S batteries,and sorted out the existing challen ges for different multivalent M-S batteries according to sulfur cathode,electrolytes,metallic an ode and current collectors/separators,respectively.In this literature,we have surveyed and exemplified the strategies developed for better M-S batteries to strengthen the application of green,cost-effective and high energy density M-S batteries.展开更多
基金supported by the China Petrochemical Corporation(222260).
文摘Metallic lithium(Li)is considered the“Holy Grail”anode material for the nextgeneration of Li batteries with high energy density owing to the extraordinary theoretical specific capacity and the lowest negative electrochemical potential.However,owing to inhomogeneous Li-ion flux,Li anodes undergo uncontrollable Li deposition,leading to limited power output and practical applications.Carbon materials and their composites with controllable structures and properties have received extensive attention to guide the homogeneous growth of Li to achieve high-performance Li anodes.In this review,the correlation between the behavior of Li anode and the properties of carbon materials is proposed.Subsequently,we review emerging strategies for rationally designing high-performance Li anodes with carbon materials,including interface engineering(stabilizing solid electrolyte interphase layer and other functionalized interfacial layer)and architecture design of host carbon(constructing three-dimension structure,preparing hollow structure,introducing lithiophilic sites,optimizing geometric effects,and compositing with Li).Based on the insights,some prospects on critical challenges and possible future research directions in this field are concluded.It is anticipated that further innovative works on the fundamental chemistry and theoretical research of Li anodes are needed.
基金supported by the National Natural Science Foundation of China(NFSC)(No.31371473 to D.Y.,No.32270888 to D.Y.and No.31970783 to D.Y.)program for Top talent Distinguished Professor from Chongqing Medical University[No.(2021)215 to D.Y.]program for Youth Innovation in Future Medicine from Chongqing Medical University(No.W0060 to D.Y.)。
文摘Tooth germ injury can lead to abnormal tooth development and even tooth loss,affecting various aspects of the stomatognathic system including form,function,and appearance.However,the research about tooth germ injury model on cellular and molecule mechanism of tooth germ repair is still very limited.Therefore,it is of great importance for the prevention and treatment of tooth germ injury to study the important mechanism of tooth germ repair by a tooth germ injury model.Here,we constructed a Tg(dlx2b:Dendra2-NTR)transgenic line that labeled tooth germ specifically.Taking advantage of the NTR/Mtz system,the dlx2b+tooth germ cells were depleted by Mtz effectively.The process of tooth germ repair was evaluated by antibody staining,in situ hybridization,Ed U staining and alizarin red staining.The severely injured tooth germ was repaired in several days after Mtz treatment was stopped.In the early stage of tooth germ repair,the expression of phosphorylated 4E-BP1 was increased,indicating that mTORC1 is activated.Inhibition of mTORC1 signaling in vitro or knockdown of mTORC1 signaling in vivo could inhibit the repair of injured tooth germ.Normally,mouse incisors were repaired after damage,but inhibition/promotion of mTORC1 signaling inhibited/promoted this repair progress.Overall,we are the first to construct a stable and repeatable repair model of severe tooth germ injury,and our results reveal that mTORC1 signaling plays a crucial role during tooth germ repair,providing a potential target for clinical treatment of tooth germ injury.
基金funded by the National Key Research and Development Program of China(No.2019YFC1803601)the National Natural Science Foundation of China(No.42177392)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2021zzts0122)。
基金supported by the National Natural Science Foundation of China (Grant No.22075028).
文摘Rechargeable aluminum batteries(RABs)are attractive cadidates for next-generation energy storage and conversion,due to the low cost and high safety of Al resources,and high capacity of metal Al based on the three-electrons reaction mechanism.However,the development of RABs is greatly limited,because of the lack of advanced cathode materials,and their complicated and unclear reaction mechanisms.Exploring the novel nanostructured transition metal and carbon composites is an effective route for obtaining ideal cathode materials.In this work,we synthesize porous CoSnO_(3)/C nanocubes with oxygen vacancies for utilizing as cathodes in RABs for the first time.The intrinsic structure stability of the mixed metal cations and carbon coating can improve the cycling performance of cathodes by regulating the internal strains of the electrodes during volume expansion.The nanocubes with porous structures contribute to fast mass transportation which improves the rate capability.In addition to this,abundant oxygen vacancies promote the adsorption affinity of cathodes,which improves storage capacity.As a result,the CoSnO_(3)/C cathodes display an excellent reversible capacity of 292.1 mAh g^(-1) at 0.1 A g^(-1),a good rate performance with 109 mAh g^(-1) that is maintained even at 1 A g^(-1) and the provided stable cycling behavior for 500 cycles.Besides,a mechanism of intercalation of Al^(3+)within CoSnO_(3)/C cathode is proposed for the electrochemical process.Overall,this work provides a step toward the development of advanced cathode materials for RABs by engineering novel nanostructured mixed transition-metal oxides with carbon composite and proposes novel insights into chemistry for RABs.
基金supported by the National Natural Science Foundation of China(grant nos.21975026 and 22005033)the National Postdoctoral Program of China(no.BX20180037)+1 种基金China Postdoctoral Science Foundation(no.2018M640077)the Beijing Institute of Technology Research Fund Program for Young Scholars(no.XSQD-202108005).
文摘Developing effective strategies to improve the initial Coulombic efficiency(ICE)and cycling stability of hard carbon(HC)anodes for sodium-ion batteries is the key to promoting the commercial application of HC.In this paper,homotype heterojunctions are designed on HC to induce the generation of stable solid electrolyte interfaces,which can effectively increase the ICE of HC from 64.7%to 81.1%.The results show that using a simple surface engineering strategy to construct a homotypic amorphous Al_(2)O_(3) layer on the HC could shield the active sites,and further inhibit electrolyte decomposition and side effects occurrence.Particularly,due to the suppression of continuous decomposition of NaPF 6 in ester-based electrolytes,the accumulation of NaF could be reduced,leading to the formation of thinner and denser solid electrolyte interface films and a decrease in the interface resistance.The HC anode can not only improve the ICE but elevate its sodium storage performance based on this homotype heterojunction composed of HC and Al_(2)O_(3).The optimized HC anode exhibits an outstanding reversible capacity of 321.5mAhg^(−1) at 50mAg^(−1).The cycling stability is also improved effectively,and the capacity retention rate is 86.9%after 2000 cycles at 1Ag^(−1) while that of the untreated HC is only 52.6%.More importantly,the improved sodium storage behaviors are explained by electrochemical kinetic analysis.
文摘Grain growth, mechanical properties, and fracture mechanism of nickel-based GH4099 superalloy are investigated using heat treatments, tensile tests, optical microscopy (OM), and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The OM observation shows that the matrix grains (γ-grains) undergo an apparent growth during the solution treatment. The grain size diameter increases from 100 to 174 μm when the solution temperature rises from 1100℃ to 1160℃ for 30 min. When the holding time increases from 15 to 60 min at 1140℃, the grain size diameter increases from 140 to 176 μm, indicating that the γ-grain growth is more sensitive to temperature than time. Standard deviation, <em>S</em><sub>v</sub>, and the grain size distribution are utilized to characterize the microstructural uniformity. To predict the grain size more accurately, we develop the grain growth kinetics and find that the growth index is close to 5. The yield strength (<em>R</em><sub>p0.2</sub>), tensile strength (<em>R</em><sub>m</sub>), and ductility (<em>A</em><sub>f</sub>) are also measured. It is found that the effect decreases in the order cooling rate, solution temperature, time. <em>R</em><sub>p0.2</sub> reduces by 47% with the increase in the cooling rate from 1℃ to 8000℃/min, while both strength and ductility exhibit little changes with time. The SEM results show that the fracture surfaces have typical mixed brittle and ductile characteristics when specimens are subjected to water quenching and air cooling. However, a complete brittle fracture occurs under furnace cooling conditions. The EDS analysis indicates that the brittle γ' (Ni<sub>3</sub>Ti) phase precipitates around the γ-grain boundary during the slow cooling process, which is the main factor yielding the complete brittle fracture. Finally, the optimal solution treatment scheme for the GH4099 superalloy is proposed—a temperature of 1140℃ for 30 min followed by air cooling.
基金Project(41371475)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare Industry
基金Project(SKLSP201853) supported by the Fund of the State Key Laboratory of Solidification Processing in NWPU,ChinaProject(51625505) supported by the National Science Fund for Distinguished Young Scholars of China+1 种基金Project(U1537203) supported by the Key Program Project of the Joint Fund of Astronomy and National Natural Science Foundation of ChinaProject(KYQD1801) supported by the Scientific Research Foundation of Tianjin University of Technology and Education,China
基金Project(41371475)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare Industry
基金supported by the National Basic Research Program of China (Grant no. 2015CB251100)Beijing Natural Science Foundation (No. L182023)
文摘Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impedes the commercial application. The initial nucleation and low Li ions diffusion rate in the electrolyte/electrode interface dominate the deposition behavior. Therefore, a uniform and flexible interface is urgently needed. Here, a facile method is proposed to prepare a thin and porous LiF-rich layer (TPL) by the in-situ reaction of small amount of ammonium hydrogen difluoride (NH4HF2) and Li metal. The deposition morphology on Li metal anode with LiF layer is significantly flat and homogeneous owning to low lateral diffusion barrier on LiF crystals and the porous structure of TPL film. Additionally, the symmetrical cells made with such TPL Li anodes show significantly stable cycling over 100 cycles at high current density of 6 mA/cm^2. The TPL Li|LiFePO4 full cells keep over 99% capacity retention after 100 cycles at 2.0 C. This approach serves as a facile and controllable way of adjusting the protective layer on Li metal.
基金supported by the National Key R&D Program of China(No.2016YFB0100500)
文摘In this work, we report a facile route for the synthesis of Li3V2(PO4)3/C cathode material via freezedrying and then calcination. The effect of calcination temperature on the electrochemical properties of the Li3V2(PO4)3/C is also investigated. When used as a lithium-ion battery cathode, the optimized Li3V2(PO4)3/C (LVP-800) through calcination at 800 ℃ exhibits a high initial charge and discharge capacity. The excellent electrochemical performance of LVP-800 is attributed to the good crystallinity and uniform morphology of the electrode material. In addition, the residual carbon can also improve the conductivity and buffer the volume expansion during the Li-ion extraction/reinsertion. Meanwhile, charge compensation also plays an important role in excellent electrochemical performance.
基金supported by the National Key R&D Program of China:Trackling Key Technology for Development and Industrialization of Power Lithium Ion Battery with High Specific Energy (Grant No.2016YFB0100508)
文摘To meet the requirements of electronic vehicles(EVs) and hybrid electric vehicles(HEVs),the high energy density Li Ni_(0.8) Co_(0.15) Al_(0.05) O_2(NCA) cathode and Si–C anode have attracted more attention.Here we report the thermal behaviors of NCA/Si–C pouch cell during the charge/discharge processes at different current densities.The total heat generations are derived from the surface temperature change during electrochemical Li+insertion/extraction in adiabatic surrounding.The reversible heat is determined by the entropic coefficients,which are related with open-circuit voltage at different temperatures; while the irreversible heat is determined by the internal resistance,which can be obtained via V–I characteristic,electrochemical impedance spectroscopy and hybrid pulse power characterization(HPPC).During the electrochemical process,the reversible heat contributes less than 10% to total heat generation; and the heat generated in charge process is less than that in discharge process.The results of thermal behaviors analyses are conducive to understanding the safety management and paving the way for building a reliable thermal model of high energy density lithium ion battery.
基金supported by the National Natural Science Foundation of China(51804290,22075025)the Beijing Natural Science Foundation(L182023)+1 种基金the Science and Technology Project of Global Energy Interconnection Research Institute Co.Ltd.(SGGR0000WLJS1900858)the Beijing Institute of Technology Research Fund Program for Young Scholars(2019CX04092)。
文摘The dependence on portable devices and electrical vehicles has triggered the awareness on the energy storage systems with ever-growing energy density.Lithium metal batteries(LMBs)has revived and attracted considerable attention due to its high volumetric(2046 m Ah cm-3),gravimetric specific capacity(3862 m Ah g^(-1))and the lowest reduction potential(-3.04 V vs.SHE.).However,during the electrochemical process of lithium anode,the growth of lithium dendrite constitutes the biggest stumbling block on the road to LMBs application.The undesirable dendrite not only limit the Coulombic efficiency(CE)of LMBs,but also cause thermal runaway and other safety issues due to short-circuits.Understanding the mechanisms of lithium nucleation and dendrite growth provides insights to solve these problems.Herein,we summarize the electrochemical models that inherently describe the lithium nucleation and dendrite growth,such as the thermodynamic,electrodeposition kinetics,internal stress,and interface transmission models.Essential parameters of temperature,current density,internal stress and interfacial Li+flux are focused.To improve the LMBs performance,state-of-the-art optimization procedures have been developed and systematically illustrated with the intrinsic regulation principles for better lithium anode stability,including electrolyte optimization,artificial interface layers,threedimensional hosts,external field,etc.Towards practical applications of LMBs,the current development of pouch cell LMBs have been further introduced with different assembly systems and fading mechanism.However,challenges and obstacles still exist for the development of LMBs,such as in-depth understanding and in-situ observation of dendrite growth,the surface protection under extreme condition and the self-healing of solid electrolyte interface.
基金financially supported by the National Natural Science Foundation of China(No.51641206)Shandong Natural Science Foundation Project(No.ZR2015EM013)+1 种基金Special Funds for Independent Innovation and Transformation of Achievements in Shandong Province(No.2014CGZH0911)National Key R&D Program of China(No.2016YFB0100508)
文摘Li4Ti5012 (LTO) with rich R-TiO2 (17.06, 23.69, and 34.42 wt%), namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate (TBT) as the precursor. Rietveld refinement of X-ray diffraction (XRD) results show that the proportion of Li occupying 16d sites is extraordinary low and the lattice constants of LTO and R-TiO2 change with the ritanium dioxide content. EIS measurements showed that with in creasing R-TiO2 content, both its charge transfer impedance (Rct) and lithium ion diffusion coefficient (DLi) decreased. The changes of Rct and DLi caused by the increase of titanium dioxide content have synergic-antagonistic effects on the rate and cycle properties of Li4Ti5012. The rate performance is positively related to DLi, while the cycle property is negatively correlated with Rct, indicati ng that the rate performs nee is mainly related to DLi, while Rct more significantly affects the cycle performance. LTO-RT-17.06% exhibited excellent rate properties, especially under a high current density (5.0 C, 132.5 mAh/g) and LTO-RT-34.42% showed superior long-term cycle performance (0.012% capacity loss per cycle) compared to that of LTO-RT-17.06% and LTO-RT-23.69%.
基金supported by the National Basic Research Program of China(grant no.2015CB251100)Shell Global Solutions International B.V.(Agreement No.PT76419)。
文摘The past decade has witnessed the germination of rechargeable aluminum batteries(RABs)with the colossal potential to enact as a device for the large scale energy storage and conversion.The Majority of investigations are dedicated to the exploration of suitable cathode materials,while less is known about the electrode/electrolyte interfaces that determine the electrochemistry of batteries.In this perspective,we will highlight the significance of electrode/electrolyte interface for RABs,in overall kinetics and capacity retention.Emphasis will be laid on the complicated yet basic understandings of the phenomena at the interfaces,including the dendrite growth,surface Al2O3 and solid–electrolyte-interphase(SEI).And we will summarize the reported practice in effort to build better electrode/electrolyte interfaces in RAB.In the end,outlook regarding to the challenges,opportunities and directions is presented.
基金supported by the National Basic Research Program of China (Grant No. 2015CB251100)the Shell Global Solutions International B.V. (Agreement No. PT76419)。
文摘Rechargeable aluminum ion battery(AIB) with high theoretical specific capacity, abundant elements and low cost engages considerable attention as a promising next generation energy storage and conversion system. Nevertheless, to date, one of the major barriers to pursuit better AIB is the limited applicable cathode materials with the ability to store aluminum highly reversibly. Herein, a highly reversible AIB is proposed using mesoporous TiO2 microparticles(M-TiO2) as the cathode material. The improved performance of Ti O2/Al battery is ascribed to the high ionic conductivity and material stability, which is caused by the stable architecture with a mesoporous microstructure and no random aggregation of secondary particles. In addition, we conducted detailed characterization to gain deeper understanding of the Al^(3+) storage mechanism in anatase Ti O2 for AIB. Our findings demonstrate clearly that Al^(3+)can be reversibly stored in anatase TiO2 by intercalation reactions based on ionic liquid electrolyte. Especially, DFT calculations were used to investigate the accurate insertion sites of aluminum ions in M-Ti O2 and the volume changes of M-TiO2 cells during discharging. As for the controversial side reactions in AIBs, in this work, by normalized calculation, we confirm that M-Ti O2 alone participate in the redox reaction. Moreover, cyclic voltammetry(CV) test was performed to investigate the pseudocapacitive behavior.
基金supported by the National Natural Science Foundation of China(No.21975026)the Beijing Institute of Technology Research Fund Program for Young Scholars(2019CX04092)。
文摘A great deal of attention has been paid on developing plant-derived hard carbon(HC)materials as anodes for sodium-ion batteries(SIBs).So far,the regulation of HC has been handicapped by the well-known ambiguity of Na^(+)storage mechanism,which fails to differentiate the Na^(+)adsorption and Na^(+)insertion,and their relationship with the size of d-interlayer spacing and structural porosity.Herein,bagassederived HC materials have been synthesized through a combination of pyrolysis treatment and microwave activation.The combined protocol has enabled to synergistically control the d-interlayer spacing and porosity.Specifically,the microwave activation has created slit pores into HC and these pores allow for an enhanced Na^(+)adsorption with an increased sloping capacity,establishing a strong correlation between the porosity and sloping capacity.Meanwhile,the pyrolysis treatment promotes the graphitization and it contributes to an intensified Na^(+)insertion with an increased plateau capacity,proving that the plateau capacity is largely contributed by the Na^(+)insertion between interlayers.Therefore,the structural regulation of bagasse-derived HC has provided a proof on positively explaining the Na^(+)storage with HC materials.The structural changes in the pore size distribution,specific surface area,d-interlayer spacing,and the electrochemical properties have been comprehensively characterized,all supporting our understanding of Na^(+)storage mechanism.As a result,the HC sample with an optimized d-interlayer spacing and porosity has delivered an improved reversible capacity of 323.6 m Ah g^(-1) at 50 m A g^(-1).This work provides an understanding of Na^(+)storage mechanism and insights on enhancing the sloping/plateau capacity by rationally regulating the graphitization and porosity of HC materials for advanced SIBs.
基金This research was funded by grants from the Natural Science Foundation in Hubei(2018CFB349)the National Natural Sciences Foundation of China(41672155,61733016)Open Research Fund Program of Key Laboratory of Tectonics and Petroleum Resources Ministry of Education(No.TPR-2018-10).
文摘Gas drainage is carried out based on output from each coal bed throughout commingling production of coalbed methane(CBM).A reasonable drainage process should therefore initially guarantee main coal bed production and then enhance gas output from other beds.Permanent damage can result if this is not the case,especially with regard to fracture development in the main gas-producing coal bed and can greatly reduce single well output.Current theoretical models and measuring devices are inapplicable to commingled CBM drainage,however,and so large errors in predictive models cannot always be avoided.The most effective currently available method involves directly measuring gas output from each coal bed as well as determining the dominant gas-producing unit.A dynamic evaluation technique for gas output from each coal bed during commingling CBM production is therefore proposed in this study.This technique comprises a downhole measurement system combined with a theoretical calculation model.Gas output parameters(i.e.,gas-phase flow rate,temperature,pressure)are measured in this approach via a downhole measurement system;substituting these parameters into a deduced theoretical calculation model then means that gas output from each seam can be calculated to determine the main gas-producing unit.Trends in gas output from a single well or each seam can therefore be predicted.The laboratory and field test results presented here demonstrate that calculation errors in CBM outputs can be controlled within a margin of 15%and therefore conform with field use requirements.
基金supported by the National Natural Science Foundation of China (22075028)the Beijing Institute of Technology Research Fund Program for Young Scholars (2019CX04092).
文摘Multivalent metal-sulfur(M-S,where M=Mg,Al,Ca,Zn,Fe,etc.)batteries offer unique opportunities to achieve high specific capacity,elemental abundancy and cost-effectiveness beyond lithium-ion batteries(LIBs).However,the slow diffusion of multivalent-metal ions and the shuttle of soluble polysulfide result in impoverished reversible capacity and limited cycle performance of M-S(Mg-S,Al-S,Ca-S,Zn-S,Fe-S,etc.)batteries.It is a necessity to optimize the electrochemical performance,while deepening the understanding of the unique electrochemical reaction mechanism,such as the intrinsic multi-electron reaction process,polysulfides dissoluti on and the in stability of metal an odes.To solve these problems,we have summarized the state-of-the-art progress of current M-S batteries,and sorted out the existing challen ges for different multivalent M-S batteries according to sulfur cathode,electrolytes,metallic an ode and current collectors/separators,respectively.In this literature,we have surveyed and exemplified the strategies developed for better M-S batteries to strengthen the application of green,cost-effective and high energy density M-S batteries.
