Lithium metal is considered to be the most promising anode material for the next-generation rechargeable batteries. However, the uniform and dendrite-free deposition of Li metal anode is hard to achieve, hindering its...Lithium metal is considered to be the most promising anode material for the next-generation rechargeable batteries. However, the uniform and dendrite-free deposition of Li metal anode is hard to achieve, hindering its practical applications. Herein, a lightweight, free-standing and nitrogen-doped carbon nanofiber-based 3D structured conductive matrix(NCNF), which is characterized by a robust and interconnected 3D network with high doping level of 9.5 at%, is prepared by electrospinning as the current collector for Li metal anode. Uniform Li nucleation with reduced polarization and dendrite-free Li deposition are achieved because the NCNF with high nitrogen-doping level and high conductivity provide abundant and homogenous metallic Li nucleation and deposition sites. Excellent cycling stability with high coulombic efficiency are realized. The Li plated NCNF was paired with LiFePO4 to assemble the full battery, also showing high cyclic stability.展开更多
The reviving use of lithium metal anode(LMA)is one of the most promising ways to upgrade the energy density of lithium ion batteries.In the roadmap towards the real use,besides the formation of the dendrite,various ad...The reviving use of lithium metal anode(LMA)is one of the most promising ways to upgrade the energy density of lithium ion batteries.In the roadmap towards the real use,besides the formation of the dendrite,various adverse reactions due to the high activity of LMA when exposed to air or the electrolyte limit its practical applications.Learning from the packaging technology in electronic industry,we propose a wax-based coating compositing with the ion conducting poly(ethylene oxide)by a simple dip-coating technology and the prepared LMA is featured with an air-stable and waterproof surface.The LMA thus remains stable for 24 h in ambient air even with the relative humidity of 70% while retaining about85% its electrochemical capacity.More importantly,the LMA is accessible to water and when dipping in water,no obvious adverse reactions or capacity decay is observed.With the composite coating,a steady cycling performance for 500 h in symmetrical cells and a low capacity decay rate of 0.075% per cycle after 300 cycles in lithium-sulfur batteries assembled with the packaged anode have been achieved.This work demonstrates a very simple and effective LMA package technology which is easily scalable and is very promising for speeding up the industrialization of lithium-sulfur batteries and shows potentials for the large-scale production of air-sensitive electrode materials not limited to LMAs.展开更多
Conventional carbon materials cannot combine high density and high porosity,which are required in many applications,typically for energy storage under a limited space.A novel highly dense yet porous carbon has previou...Conventional carbon materials cannot combine high density and high porosity,which are required in many applications,typically for energy storage under a limited space.A novel highly dense yet porous carbon has previously been produced from a three-dimensional(3D)reduced graphene oxide(r-GO)hydrogel by evaporation-induced drying.Here the mechanism of such a network shrinkage in r-GO hydrogel is specifically illustrated by the use of water and 1,4-dioxane,which have a sole difference in surface tension.As a result,the surface tension of the evaporating solvent determines the capillary forces in the nanochannels,which causes shrinkage of the r-GO network.More promisingly,the selection of a solvent with a known surface tension can precisely tune the microstructure associated with the density and porosity of the resulting porous carbon,rendering the porous carbon materials great potential in practical devices with high volumetric performance.展开更多
Two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides (TMDs) and MXene [1-5], have attracted great attention in various applications due to their unique electronic properties, large surfac...Two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides (TMDs) and MXene [1-5], have attracted great attention in various applications due to their unique electronic properties, large surface area and sheet-like structure. However, the severe aggregation of the nanosheets (NSs) leads to the loss of accessible surface area and high ion diffusion resistance in practical uses.展开更多
Lithium(Li)metal has been regarded as one of the most promising anode materials to meet the urgent requirements for the next-generation high-energy density batteries.However,the practical use of lithium metal anode is...Lithium(Li)metal has been regarded as one of the most promising anode materials to meet the urgent requirements for the next-generation high-energy density batteries.However,the practical use of lithium metal anode is hindered by the uncontrolled growth of Li dendrites,resulting in poor cycling stability and severe safety issues.Herein,vertical graphene(VG)film grown on graphite paper(GP)as an all-carbon current collector was utilized to regulate the uniform Li nucleation and suppress the growth of dendrites.The high surface area VG grown on GP not only reduces the local current density to the uniform electric field but also allows fast ion transport to homogenize the ion gradients,thus regulating the Li deposition to suppress the dendrite growth.The Li deposition can be further guided with the lithiation reaction between graphite paper and Li metal,which helps to increase lithiophilicity and reduce the Li nucleation barrier as well as the overpotential.As a result,the VG film-based anode demonstrates a stable cycling performance at a current density higher than 5mAcm^(-2)in half cells and a small hysteresis of 50mV at 1mAcm^(-2)in symmetric cells.This work provides an efficient strategy for the rational design of highly stable Li metal anodes.展开更多
Polymeric monoliths are of great interest in a variety of applications.A new gelation approach to produce a mechanically stable polystyrene(PS)gel directly from its microemulsion is reported.To produce a PS gel,the as...Polymeric monoliths are of great interest in a variety of applications.A new gelation approach to produce a mechanically stable polystyrene(PS)gel directly from its microemulsion is reported.To produce a PS gel,the as-prepared microemulsion is first demulsified by adding selected watermiscible organic solvents.The small PS latex particles liberated from the surfactant are assembled into a piece of bulk material at an appropriate temperature with a high degree of entanglement of the polymer chains.It is found that the d2 T/ηvalue is an important parameter to evaluate the gelation ability of the organic solvents and helps determine the gelation conditions.Finally,PS monoliths are obtained by capillary drying and their pore structures can be effectively tuned by changing the gelation time and the amount of solvent exchanged with water.This allows the controlled preparation of bulk PS artefacts with densities in the range of 0.06 to 1.14 g cm^(-3).This simple method of PS monolith production avoids the use of shaping tools or chemical templates,needs less energy,and is a promising alternative approach to design either integrated porous or compact polymer materials.展开更多
基金the financial support from the Guangdong Natural Science Funds for Distinguished Young Scholar (2017B030306006) the National Natural Science Foundation of China (51772164, U1601206 and U1710256)+1 种基金 the National Key Basic Research Program of China (2014CB932400)Shenzhen Technical Plan Project (JCYJ20150529164918734 and JCYJ20170412171359175)
文摘Lithium metal is considered to be the most promising anode material for the next-generation rechargeable batteries. However, the uniform and dendrite-free deposition of Li metal anode is hard to achieve, hindering its practical applications. Herein, a lightweight, free-standing and nitrogen-doped carbon nanofiber-based 3D structured conductive matrix(NCNF), which is characterized by a robust and interconnected 3D network with high doping level of 9.5 at%, is prepared by electrospinning as the current collector for Li metal anode. Uniform Li nucleation with reduced polarization and dendrite-free Li deposition are achieved because the NCNF with high nitrogen-doping level and high conductivity provide abundant and homogenous metallic Li nucleation and deposition sites. Excellent cycling stability with high coulombic efficiency are realized. The Li plated NCNF was paired with LiFePO4 to assemble the full battery, also showing high cyclic stability.
基金supported by the National Science Fund for Distinguished Young Scholars, China (51525204)National Natural Science Foundation of China (51772164 and U1601206)+3 种基金Guangdong Natural Science Funds for Distinguished Young Scholar (2017B030306006)Guangdong Special Support Program (2017TQ04C664)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01N111)the Shenzhen Basic Research Project (JCYJ20170412171630020 and JCYJ20170412171359175)
文摘The reviving use of lithium metal anode(LMA)is one of the most promising ways to upgrade the energy density of lithium ion batteries.In the roadmap towards the real use,besides the formation of the dendrite,various adverse reactions due to the high activity of LMA when exposed to air or the electrolyte limit its practical applications.Learning from the packaging technology in electronic industry,we propose a wax-based coating compositing with the ion conducting poly(ethylene oxide)by a simple dip-coating technology and the prepared LMA is featured with an air-stable and waterproof surface.The LMA thus remains stable for 24 h in ambient air even with the relative humidity of 70% while retaining about85% its electrochemical capacity.More importantly,the LMA is accessible to water and when dipping in water,no obvious adverse reactions or capacity decay is observed.With the composite coating,a steady cycling performance for 500 h in symmetrical cells and a low capacity decay rate of 0.075% per cycle after 300 cycles in lithium-sulfur batteries assembled with the packaged anode have been achieved.This work demonstrates a very simple and effective LMA package technology which is easily scalable and is very promising for speeding up the industrialization of lithium-sulfur batteries and shows potentials for the large-scale production of air-sensitive electrode materials not limited to LMAs.
基金This work was supported by the National Natural Science Fund for the Distinguished Young Scholars,China(51525204)the National Natural Science Foundation of China(51702229 and 51872195)the CAS Key Laboratory of Carbon Materials(KLCM KFJJ1704).
文摘Conventional carbon materials cannot combine high density and high porosity,which are required in many applications,typically for energy storage under a limited space.A novel highly dense yet porous carbon has previously been produced from a three-dimensional(3D)reduced graphene oxide(r-GO)hydrogel by evaporation-induced drying.Here the mechanism of such a network shrinkage in r-GO hydrogel is specifically illustrated by the use of water and 1,4-dioxane,which have a sole difference in surface tension.As a result,the surface tension of the evaporating solvent determines the capillary forces in the nanochannels,which causes shrinkage of the r-GO network.More promisingly,the selection of a solvent with a known surface tension can precisely tune the microstructure associated with the density and porosity of the resulting porous carbon,rendering the porous carbon materials great potential in practical devices with high volumetric performance.
基金supported by the National Natural Science Foundation of China (51772164 and U1601206)Guangdong Natural Science Funds for Distinguished Young Scholar (2017B030306006)+2 种基金Guangdong Special Support Program (2017TQ04C664)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01N111)Shenzhen Technical Plan Project (JCYJ20170412171630020 and JCYJ20170412171359175)
文摘Two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides (TMDs) and MXene [1-5], have attracted great attention in various applications due to their unique electronic properties, large surface area and sheet-like structure. However, the severe aggregation of the nanosheets (NSs) leads to the loss of accessible surface area and high ion diffusion resistance in practical uses.
基金We appreciate support from the National Key Research and Development Program of China(2018YFE0124500 and 2019YFA0705700)the National Natural Science Foundation of China(Nos.51972190 and 51932005)+4 种基金the National Science Fund for Distinguished Young Scholars,China(No.51525204)the Guangdong Natural Science Funds for Distinguished Young Scholars(2017B030306006)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01N111)the Shenzhen Basic Research Project(Grant Nos.JCYJ20170412171359175 and JCYJ20180508152037520)the Shenzhen Graphene Manufacturing Innovation Center(201901161513 and 201901171523).
文摘Lithium(Li)metal has been regarded as one of the most promising anode materials to meet the urgent requirements for the next-generation high-energy density batteries.However,the practical use of lithium metal anode is hindered by the uncontrolled growth of Li dendrites,resulting in poor cycling stability and severe safety issues.Herein,vertical graphene(VG)film grown on graphite paper(GP)as an all-carbon current collector was utilized to regulate the uniform Li nucleation and suppress the growth of dendrites.The high surface area VG grown on GP not only reduces the local current density to the uniform electric field but also allows fast ion transport to homogenize the ion gradients,thus regulating the Li deposition to suppress the dendrite growth.The Li deposition can be further guided with the lithiation reaction between graphite paper and Li metal,which helps to increase lithiophilicity and reduce the Li nucleation barrier as well as the overpotential.As a result,the VG film-based anode demonstrates a stable cycling performance at a current density higher than 5mAcm^(-2)in half cells and a small hysteresis of 50mV at 1mAcm^(-2)in symmetric cells.This work provides an efficient strategy for the rational design of highly stable Li metal anodes.
基金financially supported by the National Science Fund for Distinguished Young Scholars of China(51525204)the National Natural Science Foundation of China(51702229)。
文摘Polymeric monoliths are of great interest in a variety of applications.A new gelation approach to produce a mechanically stable polystyrene(PS)gel directly from its microemulsion is reported.To produce a PS gel,the as-prepared microemulsion is first demulsified by adding selected watermiscible organic solvents.The small PS latex particles liberated from the surfactant are assembled into a piece of bulk material at an appropriate temperature with a high degree of entanglement of the polymer chains.It is found that the d2 T/ηvalue is an important parameter to evaluate the gelation ability of the organic solvents and helps determine the gelation conditions.Finally,PS monoliths are obtained by capillary drying and their pore structures can be effectively tuned by changing the gelation time and the amount of solvent exchanged with water.This allows the controlled preparation of bulk PS artefacts with densities in the range of 0.06 to 1.14 g cm^(-3).This simple method of PS monolith production avoids the use of shaping tools or chemical templates,needs less energy,and is a promising alternative approach to design either integrated porous or compact polymer materials.
