A modified cellular automaton model is developed to depict the interface evolution inside the cementite plus ferrite lamellar microstructures during the reaustenitization of a pearlite steel. In this model, migrations...A modified cellular automaton model is developed to depict the interface evolution inside the cementite plus ferrite lamellar microstructures during the reaustenitization of a pearlite steel. In this model, migrations of both the austenite- ferrite and austenite-cementite interfaces coupled with the carbon diffusion and redistribution are integrated. The capil- laxity effect derived from local interface curvatures is also carefully considered by involving the concentration given by the phase diagram modified by the Gibbs-Thomson effect. This allows the interface evolution from a transient state to a steady state under different annealing conditions and various interlamellar spacings to be simulated. The proposed cellular automaton approach could be readily used to describe the kinetics of austenite formation from the lamellar pearlites and virtually reveal the kinematics of the moving interfaces from the microstructural aspect.展开更多
This review summarizes the work carried out in the field of interface study in carbon nanotube reinforced aluminum （CNT/A1） composites. Much research work has been conducted to reveal the evolution of CNT/A1 interfa...This review summarizes the work carried out in the field of interface study in carbon nanotube reinforced aluminum （CNT/A1） composites. Much research work has been conducted to reveal the evolution of CNT/A1 interface in producing the composite with the purpose of achieving uniform distribution of CNTs and tight interfacial bonding. The effect and principles of coating were reviewed along with the illustration of ＂intermetallic interphases＂ design. Different roles of CNT/Al interface in structural and functional application were elucidated, and the future work that needs attention was addressed.展开更多
Lithium-ion batteries are at the forefront of modern energy storage technology.However,the accumulation of by-products such as ethylene and carbon dioxide during charging and discharging cycles reduces battery effecti...Lithium-ion batteries are at the forefront of modern energy storage technology.However,the accumulation of by-products such as ethylene and carbon dioxide during charging and discharging cycles reduces battery effective capacity and threatens large-scale safe performance.With significant advantages over ethylene carbonate(EC)electrolytes,fluorinated electrolytes can more effectively suppress internal gas evolution,thereby improving battery safety and cycling stability.To reveal the mechanism behind gas formation in lithium-ion batteries,our study investigated the transport behavior and interfacial products of fluorinated electrolytes under various operation conditions,including electrode material and electrolyte composition.Innovatively,we applied the reaction network integrator ReacNetGenerator to the analysis of the solid electrolyte interface(SEI)in lithium batteries,providing more molecular fingerprint information from the perspective of specific products.Using reactive molecular dynamics(MD)simulations with the ReaxFF force field and EChemDID,complemented by density functional theory(DFT)calculations,our results demonstrate that fluorinated electrolytes can effectively suppress the decomposition of LiPF_(6) to produce toxic gases PFs and PF_3.DFT analysis further reveals that highly fluorinated solvents(e.g.,FEMC)enhance the anti-reduction stability of PF_(6)~-through synergistic regulation of molecular orbital energy levels,thermodynamic electron affinity,charge transfer,and electrostatic potential distribution,thereby mitigating LiPF_(6) decomposition.Additionally,fluorinated electrolytes generate significantly more LiF components than non-fluorinated ones to promote the formation of a stable and durable solid electrolyte interface(SEI).Experimental validations via XPS and GC-MS confirm reduced CO_(2) generation and LiF-enriched SEI formation,aligning with simulation and DFT data.The findings provide valuable insights for the design of advanced electrolytes aimed at ensuring large-scale,safe energy storage solutions.展开更多
Garnet-type solid-state electrolytes(SSEs)are particularly attractive in the construction of all-solid-state lithium(Li)batteries due to their high ionic conductivity,wide electrochemical window and remarkable(electro...Garnet-type solid-state electrolytes(SSEs)are particularly attractive in the construction of all-solid-state lithium(Li)batteries due to their high ionic conductivity,wide electrochemical window and remarkable(electro)chemical stability.However,the intractable issues of poor cathode/garnet interface and general low cathode loading hinder their practical application.Herein,we demonstrate the construction of a reinforced cathode/garnet interface by spark plasma sintering,via co-sintering Li_(6.5)La_(3)Zr_(1.5)Ta_(0.5)O_(12)(LLZTO)electrolyte powder and LiCoO_(2)/LLZTO composite cathode powder directly into a dense dual-layer with 5 wt%Li_(3)BO_(3)as sintering additive.The bulk composite cathode with LiCoO_(2)/LLZTO cross-linked structure is firmly welded to the LLZTO layer,which optimizes both Li-ion and electron transport.Therefore,the one-step integrated sintering process implements an ultra-low cathode/garnet interfacial resistance of 3.9Ωcm^(2)(100◦C)and a high cathode loading up to 2.02 mAh cm^(−2).Moreover,the Li_(3)BO_(3)reinforced LiCoO_(2)/LLZTO interface also effectively mitigates the strain/stress of LiCoO_(2),which facilitates the achieving of superior cycling stability.The bulk-type Li|LLZTO|LiCoO_(2)-LLZTO full cell with areal capacity of 0.73 mAh cm^(−2)delivers capacity retention of 81.7%after 50 cycles at 100μA cm^(−2).Furthermore,we reveal that non-uniform Li plating/stripping leads to the formation of gaps and finally results in the separation of Li and LLZTO electrolyte during long-term cycling,which becomes the dominant capacity decay mechanism in high-capacity full cells.This work provides insight into the degradation of Li/SSE interface and a strategy to radically improve the electrochemical performance of garnet-based all-solid-state Li batteries.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51371169 and 51401214)
文摘A modified cellular automaton model is developed to depict the interface evolution inside the cementite plus ferrite lamellar microstructures during the reaustenitization of a pearlite steel. In this model, migrations of both the austenite- ferrite and austenite-cementite interfaces coupled with the carbon diffusion and redistribution are integrated. The capil- laxity effect derived from local interface curvatures is also carefully considered by involving the concentration given by the phase diagram modified by the Gibbs-Thomson effect. This allows the interface evolution from a transient state to a steady state under different annealing conditions and various interlamellar spacings to be simulated. The proposed cellular automaton approach could be readily used to describe the kinetics of austenite formation from the lamellar pearlites and virtually reveal the kinematics of the moving interfaces from the microstructural aspect.
基金financially supported by the National Basic Research Program of China (No.2012CB619600)the National Natural Science Foundation of China (Nos.51131004,51071100,and 51001071)+1 种基金the National High Technology Research and Development Program of China (No.2012AA030311)Shanghai Science & Technology Committee (Nos.11JC1405500)
文摘This review summarizes the work carried out in the field of interface study in carbon nanotube reinforced aluminum （CNT/A1） composites. Much research work has been conducted to reveal the evolution of CNT/A1 interface in producing the composite with the purpose of achieving uniform distribution of CNTs and tight interfacial bonding. The effect and principles of coating were reviewed along with the illustration of ＂intermetallic interphases＂ design. Different roles of CNT/Al interface in structural and functional application were elucidated, and the future work that needs attention was addressed.
基金funding support from the National Natural Science Foundation of China(Grant No.52302302)the National Key R&D Program of China(Grant No.2022YFE0208000)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Special Funds of Tongji University for‘‘Sino-German Cooperation 2.0 Strategy”。
文摘Lithium-ion batteries are at the forefront of modern energy storage technology.However,the accumulation of by-products such as ethylene and carbon dioxide during charging and discharging cycles reduces battery effective capacity and threatens large-scale safe performance.With significant advantages over ethylene carbonate(EC)electrolytes,fluorinated electrolytes can more effectively suppress internal gas evolution,thereby improving battery safety and cycling stability.To reveal the mechanism behind gas formation in lithium-ion batteries,our study investigated the transport behavior and interfacial products of fluorinated electrolytes under various operation conditions,including electrode material and electrolyte composition.Innovatively,we applied the reaction network integrator ReacNetGenerator to the analysis of the solid electrolyte interface(SEI)in lithium batteries,providing more molecular fingerprint information from the perspective of specific products.Using reactive molecular dynamics(MD)simulations with the ReaxFF force field and EChemDID,complemented by density functional theory(DFT)calculations,our results demonstrate that fluorinated electrolytes can effectively suppress the decomposition of LiPF_(6) to produce toxic gases PFs and PF_3.DFT analysis further reveals that highly fluorinated solvents(e.g.,FEMC)enhance the anti-reduction stability of PF_(6)~-through synergistic regulation of molecular orbital energy levels,thermodynamic electron affinity,charge transfer,and electrostatic potential distribution,thereby mitigating LiPF_(6) decomposition.Additionally,fluorinated electrolytes generate significantly more LiF components than non-fluorinated ones to promote the formation of a stable and durable solid electrolyte interface(SEI).Experimental validations via XPS and GC-MS confirm reduced CO_(2) generation and LiF-enriched SEI formation,aligning with simulation and DFT data.The findings provide valuable insights for the design of advanced electrolytes aimed at ensuring large-scale,safe energy storage solutions.
基金This work was supported by the National Key R&D Program of China(Grant No.2021YFB2401800)the National Natural Science Foundation of China(Grants Nos.21875196,22279108,21935009 and 22021001)the Fundamental Research Funds for Xiamen University(No.20720202019).
文摘Garnet-type solid-state electrolytes(SSEs)are particularly attractive in the construction of all-solid-state lithium(Li)batteries due to their high ionic conductivity,wide electrochemical window and remarkable(electro)chemical stability.However,the intractable issues of poor cathode/garnet interface and general low cathode loading hinder their practical application.Herein,we demonstrate the construction of a reinforced cathode/garnet interface by spark plasma sintering,via co-sintering Li_(6.5)La_(3)Zr_(1.5)Ta_(0.5)O_(12)(LLZTO)electrolyte powder and LiCoO_(2)/LLZTO composite cathode powder directly into a dense dual-layer with 5 wt%Li_(3)BO_(3)as sintering additive.The bulk composite cathode with LiCoO_(2)/LLZTO cross-linked structure is firmly welded to the LLZTO layer,which optimizes both Li-ion and electron transport.Therefore,the one-step integrated sintering process implements an ultra-low cathode/garnet interfacial resistance of 3.9Ωcm^(2)(100◦C)and a high cathode loading up to 2.02 mAh cm^(−2).Moreover,the Li_(3)BO_(3)reinforced LiCoO_(2)/LLZTO interface also effectively mitigates the strain/stress of LiCoO_(2),which facilitates the achieving of superior cycling stability.The bulk-type Li|LLZTO|LiCoO_(2)-LLZTO full cell with areal capacity of 0.73 mAh cm^(−2)delivers capacity retention of 81.7%after 50 cycles at 100μA cm^(−2).Furthermore,we reveal that non-uniform Li plating/stripping leads to the formation of gaps and finally results in the separation of Li and LLZTO electrolyte during long-term cycling,which becomes the dominant capacity decay mechanism in high-capacity full cells.This work provides insight into the degradation of Li/SSE interface and a strategy to radically improve the electrochemical performance of garnet-based all-solid-state Li batteries.
