Pore structure of hard carbon has a fundamental influence on the electrochemical properties in sodium-ion batteries(SIBs).Ultra-micropores(<0.5 nm)of hard carbon can function as ionic sieves to reduce the diffusion...Pore structure of hard carbon has a fundamental influence on the electrochemical properties in sodium-ion batteries(SIBs).Ultra-micropores(<0.5 nm)of hard carbon can function as ionic sieves to reduce the diffusion of slovated Na+but allow the entrance of naked Na^(+) into the pores,which can reduce the interficial contact between the electrolyte and the inner pores without sacrificing the fast diffusion kinetics.Herein,a molten diffusion-carbonization method is proposed to transform the micropores(>1 nm)inside carbon into ultra-micropores(<0.5 nm).Consequently,the designed carbon anode displays an enhanced capacity of 346 mAh g^(−1) at 30 mA g^(−1) with a high ICE value of~80.6%and most of the capacity(~90%)is below 1 V.Moreover,the high-loading electrode(~19 mg cm^(−2))exhibits a good temperature endurance with a high areal capacity of 6.14 mAh cm^(−2) at 25℃ and 5.32 mAh cm^(−2) at −20℃.Based on the in situ X-ray diffraction and ex situ solid-state nuclear magnetic resonance results,the designed ultra-micropores provide the extra Na+storage sites,which mainly contributes to the enhanced capacity.This proposed strategy shows a good potential for the development of high-performance SIBs.展开更多
The development of efficient metal-zeolite bifunctional catalysts for catalytic fast pyrolysis(CFP) of biomass waste is highly desirable for bioenergy and renewable biofuel production.However,conventional metal-loaded...The development of efficient metal-zeolite bifunctional catalysts for catalytic fast pyrolysis(CFP) of biomass waste is highly desirable for bioenergy and renewable biofuel production.However,conventional metal-loaded zeolites often suffer from metal sintering during pyrolysis and are thus inactivated.In this study,single-site Ga-functionalized hollow ZSM-5(GaO_x@HS-Z5) was synthesized via an impregnationdissolution-recrystallization strategy without H_(2) reduction.The Ga atom was coordinated to four oxygen atoms in HS-Z5 frameworks.Benefitting from the highly dispersed single-Ga atoms and hollow zeolite framework,3GaO_x@HS-Z5 performed the best in producing hydrocarbon-rich bio-oil compared to impregnated 3GaO_x/HS-Z5 and H_(2)-reduced 3Ga@HS-Z5 in the maize straw CFP.In particular,3GaO_x@HS-Z5 delivered the highest bio-oil yield(23.6 wt%) and hydrocarbon selectivity(49.4 area%).3GaO_x@HS-Z5 also retained its structural integrity and catalytic activity after five pyrolysis-regeneration cycles,demonstrating its advantage in practical biomass CFP.The elimination of H_(2) reduction during the synthesis of catalyst provides an additional advantage for simplifying the CFP process and reducing operating costs.The retained Ga micro-environment and anti-sintering properties were unique for 3GaO_x@HS-Z5,as severe metal sintering occurred during pyrolysis for other metals(e.g.,NiO_x,ZnO_x,FeO_x,and CoO_x) that encapsulated HS-Z5.展开更多
Silicon is being investigated extensively as an anodic material for next-generation lithium ion batteries for portable energy storage and electric vehicles.However,the large changes in volume during cycling lead to th...Silicon is being investigated extensively as an anodic material for next-generation lithium ion batteries for portable energy storage and electric vehicles.However,the large changes in volume during cycling lead to the breakdown of the conductive network in Si anodes and the formation of an unstable solid-electrolyte interface,resulting in capacity fading.Here,we demonstrate nanoparticles with a Si@Mn22.6Si5.4C4@C double-shell structure and the formation of self-organized Si-Mn-C nanocomposite anodes during the lithiation/delithiation process.The anode consists of amorphous Si particles less than 10 nm in diameter and separated by an interconnected conductive/buffer network,which exhibits excellent charge transfer kinetics and charge/discharge performances.A stable specific capacity of 1100 mAh·g-1 at 100 mA·g-1 and a coulombic efficiency of 99.2%after 30 cycles are achieved.Additionally,a rate capacity of 343 mAh·g-1 and a coulombic efficiency of 99.4%at 12000 mA·g-1 are also attainable.Owing to its simplicity and applicability,this strategy for improving electrode performance paves a way for the development of high-performance Si-based anodic materials for lithium ion batteries.展开更多
The development of all-solid-state lithium batteries(ASSLBs)depends on exploiting solid-state electrolytes(SSEs)with high ionic conductivity and electrochemical stability.Fluorination is generally considered to be an ...The development of all-solid-state lithium batteries(ASSLBs)depends on exploiting solid-state electrolytes(SSEs)with high ionic conductivity and electrochemical stability.Fluorination is generally considered to be an effective strategy to improve the ionic conductivity and electrochemical stability of inorganic SSEs.Here,we report the partial fluorination of the chlo rine sites in an antiperovskite,by which the orthorhombic Li_(2)OHCl was transformed into cubic Li_(2)OHCl_(0.9)F_(0.1),resulting in a fourfold increase in ionic conductivity at 30℃.The ab initio molecular dynamics simulations suggest that both the crystal symmetry and the anions electronegativity influence the diffusion of Li+in the antiperovskite structure.Besides,from the perspective of experiments and calculations,it is confirmed that fluorination is a feasible method to improve the electrochemical stability of antiperovskite SSEs.The LiFePO_(4)|Li cell based on Li_(2)OHCl_(0.9)F_(0.1) is also assembled and exhibits stable cycle performance,which indicates that fluorination of antiperovskite SSEs is an effective way to produce high-performance SSEs for practical application of ASSLBs.展开更多
基金Singapore MOE Tier Ⅱ grant R143-000-A29-112the National Research Foundation under the Grant of NRF2017NRF-NSFC001-007.
文摘Pore structure of hard carbon has a fundamental influence on the electrochemical properties in sodium-ion batteries(SIBs).Ultra-micropores(<0.5 nm)of hard carbon can function as ionic sieves to reduce the diffusion of slovated Na+but allow the entrance of naked Na^(+) into the pores,which can reduce the interficial contact between the electrolyte and the inner pores without sacrificing the fast diffusion kinetics.Herein,a molten diffusion-carbonization method is proposed to transform the micropores(>1 nm)inside carbon into ultra-micropores(<0.5 nm).Consequently,the designed carbon anode displays an enhanced capacity of 346 mAh g^(−1) at 30 mA g^(−1) with a high ICE value of~80.6%and most of the capacity(~90%)is below 1 V.Moreover,the high-loading electrode(~19 mg cm^(−2))exhibits a good temperature endurance with a high areal capacity of 6.14 mAh cm^(−2) at 25℃ and 5.32 mAh cm^(−2) at −20℃.Based on the in situ X-ray diffraction and ex situ solid-state nuclear magnetic resonance results,the designed ultra-micropores provide the extra Na+storage sites,which mainly contributes to the enhanced capacity.This proposed strategy shows a good potential for the development of high-performance SIBs.
基金supported by the National Natural Science Foundation of China (2217600921906005)+3 种基金the Beijing Natural Science Foundation (8222064)the Bingtuan Science and Technology Program (2023CB008-21)the CNPC Innovation Foundation (2022DQ02-0406)the financial support from Beihang University。
文摘The development of efficient metal-zeolite bifunctional catalysts for catalytic fast pyrolysis(CFP) of biomass waste is highly desirable for bioenergy and renewable biofuel production.However,conventional metal-loaded zeolites often suffer from metal sintering during pyrolysis and are thus inactivated.In this study,single-site Ga-functionalized hollow ZSM-5(GaO_x@HS-Z5) was synthesized via an impregnationdissolution-recrystallization strategy without H_(2) reduction.The Ga atom was coordinated to four oxygen atoms in HS-Z5 frameworks.Benefitting from the highly dispersed single-Ga atoms and hollow zeolite framework,3GaO_x@HS-Z5 performed the best in producing hydrocarbon-rich bio-oil compared to impregnated 3GaO_x/HS-Z5 and H_(2)-reduced 3Ga@HS-Z5 in the maize straw CFP.In particular,3GaO_x@HS-Z5 delivered the highest bio-oil yield(23.6 wt%) and hydrocarbon selectivity(49.4 area%).3GaO_x@HS-Z5 also retained its structural integrity and catalytic activity after five pyrolysis-regeneration cycles,demonstrating its advantage in practical biomass CFP.The elimination of H_(2) reduction during the synthesis of catalyst provides an additional advantage for simplifying the CFP process and reducing operating costs.The retained Ga micro-environment and anti-sintering properties were unique for 3GaO_x@HS-Z5,as severe metal sintering occurred during pyrolysis for other metals(e.g.,NiO_x,ZnO_x,FeO_x,and CoO_x) that encapsulated HS-Z5.
基金supported by the Major Program of Beijing Municipal Natural Science Foundation(No.2110001)the National Natural Science Foundation of China(No.11179001)the National High Technology Research and Development Program(No.2012AA052201)
文摘Silicon is being investigated extensively as an anodic material for next-generation lithium ion batteries for portable energy storage and electric vehicles.However,the large changes in volume during cycling lead to the breakdown of the conductive network in Si anodes and the formation of an unstable solid-electrolyte interface,resulting in capacity fading.Here,we demonstrate nanoparticles with a Si@Mn22.6Si5.4C4@C double-shell structure and the formation of self-organized Si-Mn-C nanocomposite anodes during the lithiation/delithiation process.The anode consists of amorphous Si particles less than 10 nm in diameter and separated by an interconnected conductive/buffer network,which exhibits excellent charge transfer kinetics and charge/discharge performances.A stable specific capacity of 1100 mAh·g-1 at 100 mA·g-1 and a coulombic efficiency of 99.2%after 30 cycles are achieved.Additionally,a rate capacity of 343 mAh·g-1 and a coulombic efficiency of 99.4%at 12000 mA·g-1 are also attainable.Owing to its simplicity and applicability,this strategy for improving electrode performance paves a way for the development of high-performance Si-based anodic materials for lithium ion batteries.
基金supported by the National Key Research and Development Program of China(2020YFA0210701)the National Natural Science Foundation of China(22005134,12275119,U22A20439)+4 种基金the Shenzhen Science and Technology Program(RCBS20210609103647030)the Guangdong Basic and Applied Basic Research Foundation(2021A1515012403)the Shenzhen Science and Technology Program(KQTD20200820113047086)the Guangdong-Hong Kong-Macao Joint Laboratory for PhotonicThermal-Electrical Energy Materials and Devices(2019B121205001)the open research fund of Songshan Lake Materials Laboratory(2022SLABFK04)。
文摘The development of all-solid-state lithium batteries(ASSLBs)depends on exploiting solid-state electrolytes(SSEs)with high ionic conductivity and electrochemical stability.Fluorination is generally considered to be an effective strategy to improve the ionic conductivity and electrochemical stability of inorganic SSEs.Here,we report the partial fluorination of the chlo rine sites in an antiperovskite,by which the orthorhombic Li_(2)OHCl was transformed into cubic Li_(2)OHCl_(0.9)F_(0.1),resulting in a fourfold increase in ionic conductivity at 30℃.The ab initio molecular dynamics simulations suggest that both the crystal symmetry and the anions electronegativity influence the diffusion of Li+in the antiperovskite structure.Besides,from the perspective of experiments and calculations,it is confirmed that fluorination is a feasible method to improve the electrochemical stability of antiperovskite SSEs.The LiFePO_(4)|Li cell based on Li_(2)OHCl_(0.9)F_(0.1) is also assembled and exhibits stable cycle performance,which indicates that fluorination of antiperovskite SSEs is an effective way to produce high-performance SSEs for practical application of ASSLBs.
