Metallic Li is a promising anode material for high energy density batteries but it suffers from poor stability and formation of unsafe dendrites. Previous studies demonstrated that 3 D metal foams are able to improve ...Metallic Li is a promising anode material for high energy density batteries but it suffers from poor stability and formation of unsafe dendrites. Previous studies demonstrated that 3 D metal foams are able to improve the stability of Li metal but the properties of these foams are inherently limited. Here we report a facile surface modification approach via magnetron sputtering of mixed oxides that effectively modulate the properties of Cu foams for supporting Li metal with remarkable stability. We discovered that hybrid Li anodes with Li metal thermally infused to aluminum-zinc oxides(AZO) coated Cu foams have significantly improved stability and reactivity compared with pristine Li foils and Li infused to unmodified Cu foams. Full cells assembled with a Li Fe PO4 cathode and a hybrid anode maintained low and stable charge-transfer resistance(<50) during 500 cycles in carbonate electrolytes, and exhibited superior rate capability(~100 m Ah g-1 at 20 C) along with better electrochemical reversibility and surface stability. The AZO modified Cu foams had superior mechanical strength and afforded the hybrid anodes with minimized volume change without the formation of dendrites during battery cycling. The rational construction of surface architecture to precisely control Li plating and stripping may have great implications for the practical applications of Li metal batteries.展开更多
To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanos...To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanostructured sulfur cathodes are not so promising, because of the low volumetric energy density and high cost. In this work, we obtained the low-cost, scalable, eco-friendly mass production of edge-functionalized acetylene black-sulfur(FAB-S) composites by high-energy ball-milling technique for lithium sulfur batteries. The as-prepared FAB-S composite can deliver a high initial discharge capacity of 1304 mAh/g and still remain a reversible capacity of 814 mAh/g after 200 cycles at a charge-discharge rate of 0.2 C in the voltage range of 1.7–2.7 V. The observed excellent electrochemical properties demonstrate that the cathodes obtained by the facile high-energy ball-milling method as the cathode for rechargeable Li-S batteries are of great potential because it used the sole conductive additive acetylene black(AB).Such improved properties could be attributed to the partially exfoliation of AB, which not only keeps the AB’s inherent advantage, but also increases the specific surface area and forms chemical bonds between carbon and sulfur, resulting in the accumulation of the polysulfides intermediate through both the physical and chemical routes.展开更多
Sluggish polysulfide redox kinetics,especially the high energy barrier of rate-determining short-chain polysulfide conversion and the high activation barrier of Na_(2)S decomposition during sulfur recovery,compromise ...Sluggish polysulfide redox kinetics,especially the high energy barrier of rate-determining short-chain polysulfide conversion and the high activation barrier of Na_(2)S decomposition during sulfur recovery,compromise the full potential of rechargeable Na-S electrochemistry.Herein we construct the hierarchical sandwich-structured carbon matrix with atomically dispersed Mn-N4 Lewis acidic sites,taking advantage of their bidirectional electrocatalytic behavior toward interface-mediated reversible sulfur redox.Experimental and theoretical results reveal that the spatial confinement and catalytic effects facilitated via strong Lewis acid-base electron interactions synergistically manipulate the low kinetically direct Na_(2)S_(4) to Na_(2)S conversion,and the formation of Mn-S bond minimizes the energy barrier of Na_(2)S electrochemical activation during battery recharging,thereby rendering a reversible and tunable polysulfide speciation pathway.Furthermore,the degradation of the Na-S cell is due to the depletion of metal anode rather than the loss of active sulfur species and/or aggregation of inactive dead sulfur.As expected,the S@Mn/NC cathode delivers outstanding rate capability and ultrahigh cycling stability.Simultaneously,a proof-of-concept pouch cell was also demonstrated capable of delivering an energy density up to 840 Wh kgcathode−1.The tunable sulfur redox electrochemistry invoked by the bidirectional monodispersed Mn catalytic hot spots facilitates the efficient polysulfide speciation for practical Na-S cells.展开更多
To date, Wald sequential probability ratio test(WSPRT) has been widely applied to track management of multiple hypothesis tracking(MHT). But in a real situation, if the false alarm spatial density is much larger than ...To date, Wald sequential probability ratio test(WSPRT) has been widely applied to track management of multiple hypothesis tracking(MHT). But in a real situation, if the false alarm spatial density is much larger than the new target spatial density, the original track score will be very close to the deletion threshold of the WSPRT. Consequently, all tracks, including target tracks, may easily be deleted, which means that the tracking performance is sensitive to the tracking environment. Meanwhile, if a target exists for a long time, its track will have a high score, which will make the track survive for a long time even after the target has disappeared. In this paper, to consider the relationship between the hypotheses of the test, we adopt the Shiryayev SPRT(SSPRT) for track management in MHT. By introducing a hypothesis transition probability, the original track score can increase faster, which solves the first problem. In addition, by setting an independent SSPRT for track deletion, the track score can decrease faster, which solves the second problem. The simulation results show that the proposed SSPRT-based MHT can achieve better tracking performance than MHT based on the WSPRT under a high false alarm spatial density.展开更多
Graphene nanoscrolls with one-dimensional topological structure obtained by Archimedean-type spirals of graphene,inherit the intrinsic properties of the pristine graphene.They have some unique advantages,including ope...Graphene nanoscrolls with one-dimensional topological structure obtained by Archimedean-type spirals of graphene,inherit the intrinsic properties of the pristine graphene.They have some unique advantages,including open edges/ends,adjustable internal volume,and diameter.Notably,the accommodation of functionalized components in their open interlayer is potentially a fantastic strategy to promote the epoch-making progress in nanotechnology areas,including energy storage,environmental remediation,biotechnology,and smart devices.However,it could destroy the driving forces for the self-rolling of graphene nanosheets and thus it is still a challenge to prepare functionalized graphene nanoscrolls.Here,based on density functional theory prediction,we reported a feasible method to fabricate graphene oxide nanoscrolls with carbon nanotubes as the template.The method was driven by cation-πinteractions,which were caused by metal cations that also acted as the adsorption center.Most importantly,the distinct mechanism and an acidity-dependent rule for the formation of graphene nanoscrolls were identified.Benefiting from the introduced metal cations and the macro three-dimensional hierarchical structure,the produced nanoscroll aerogel exhibited significantly improved adsorption performance toward different organic solvents with the adsorption capacities from 129.9 to 265.7 g g^(−1).This work demonstrates a simple and efficient strategy to fabricate functionalized component-accommodated graphene nanoscroll,which could find important applications in various fields.展开更多
基金The financial supports of the National Natural Science Foundation of China(Grant Nos.51572060,51702067 and 51671074)Special Financial Grant from the China Postdoctoral Science Foundation(No.2017T100239)+1 种基金General Financial Grant from the China Postdoctoral Science Foundation(No.2016M590279)the startup grants from Northern Illinois University。
文摘Metallic Li is a promising anode material for high energy density batteries but it suffers from poor stability and formation of unsafe dendrites. Previous studies demonstrated that 3 D metal foams are able to improve the stability of Li metal but the properties of these foams are inherently limited. Here we report a facile surface modification approach via magnetron sputtering of mixed oxides that effectively modulate the properties of Cu foams for supporting Li metal with remarkable stability. We discovered that hybrid Li anodes with Li metal thermally infused to aluminum-zinc oxides(AZO) coated Cu foams have significantly improved stability and reactivity compared with pristine Li foils and Li infused to unmodified Cu foams. Full cells assembled with a Li Fe PO4 cathode and a hybrid anode maintained low and stable charge-transfer resistance(<50) during 500 cycles in carbonate electrolytes, and exhibited superior rate capability(~100 m Ah g-1 at 20 C) along with better electrochemical reversibility and surface stability. The AZO modified Cu foams had superior mechanical strength and afforded the hybrid anodes with minimized volume change without the formation of dendrites during battery cycling. The rational construction of surface architecture to precisely control Li plating and stripping may have great implications for the practical applications of Li metal batteries.
基金supported by the National Natural Science Foundation of China(Grant Nos.51671074,51602079,51572060,and 51502062)the Fundamental Research Funds for the Central Universities(No.HIT.BRETIII.201224 and 201312)+1 种基金Program for Innovation Research of Science in Harbin Institute of Technology(PIRS of HIT-No.201506)support from the Excellent Youth Foundation of Heilongjiang Scientific Committee(No.JC2015010)
文摘To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanostructured sulfur cathodes are not so promising, because of the low volumetric energy density and high cost. In this work, we obtained the low-cost, scalable, eco-friendly mass production of edge-functionalized acetylene black-sulfur(FAB-S) composites by high-energy ball-milling technique for lithium sulfur batteries. The as-prepared FAB-S composite can deliver a high initial discharge capacity of 1304 mAh/g and still remain a reversible capacity of 814 mAh/g after 200 cycles at a charge-discharge rate of 0.2 C in the voltage range of 1.7–2.7 V. The observed excellent electrochemical properties demonstrate that the cathodes obtained by the facile high-energy ball-milling method as the cathode for rechargeable Li-S batteries are of great potential because it used the sole conductive additive acetylene black(AB).Such improved properties could be attributed to the partially exfoliation of AB, which not only keeps the AB’s inherent advantage, but also increases the specific surface area and forms chemical bonds between carbon and sulfur, resulting in the accumulation of the polysulfides intermediate through both the physical and chemical routes.
基金financially supported by the Natural Scientific Foundation of China(grant nos.22109001 and 22208335)the Postdoctoral Fellowship Program of CPSF(grant no.GZB20230950)+2 种基金the Heilongjiang Postdoctoral Science Foundation(grant no.LBH-Z23187)the Jiangsu Key Laboratory for Carbon-Based Functional Materials&Devices,Soochow University(grant no.KJS2308)startup funds provided to H.Z.from the Harbin Institute of Technology.
文摘Sluggish polysulfide redox kinetics,especially the high energy barrier of rate-determining short-chain polysulfide conversion and the high activation barrier of Na_(2)S decomposition during sulfur recovery,compromise the full potential of rechargeable Na-S electrochemistry.Herein we construct the hierarchical sandwich-structured carbon matrix with atomically dispersed Mn-N4 Lewis acidic sites,taking advantage of their bidirectional electrocatalytic behavior toward interface-mediated reversible sulfur redox.Experimental and theoretical results reveal that the spatial confinement and catalytic effects facilitated via strong Lewis acid-base electron interactions synergistically manipulate the low kinetically direct Na_(2)S_(4) to Na_(2)S conversion,and the formation of Mn-S bond minimizes the energy barrier of Na_(2)S electrochemical activation during battery recharging,thereby rendering a reversible and tunable polysulfide speciation pathway.Furthermore,the degradation of the Na-S cell is due to the depletion of metal anode rather than the loss of active sulfur species and/or aggregation of inactive dead sulfur.As expected,the S@Mn/NC cathode delivers outstanding rate capability and ultrahigh cycling stability.Simultaneously,a proof-of-concept pouch cell was also demonstrated capable of delivering an energy density up to 840 Wh kgcathode−1.The tunable sulfur redox electrochemistry invoked by the bidirectional monodispersed Mn catalytic hot spots facilitates the efficient polysulfide speciation for practical Na-S cells.
基金supported by National Natural Science Foundation of China (Grant Nos. 61471019, 61501011)
文摘To date, Wald sequential probability ratio test(WSPRT) has been widely applied to track management of multiple hypothesis tracking(MHT). But in a real situation, if the false alarm spatial density is much larger than the new target spatial density, the original track score will be very close to the deletion threshold of the WSPRT. Consequently, all tracks, including target tracks, may easily be deleted, which means that the tracking performance is sensitive to the tracking environment. Meanwhile, if a target exists for a long time, its track will have a high score, which will make the track survive for a long time even after the target has disappeared. In this paper, to consider the relationship between the hypotheses of the test, we adopt the Shiryayev SPRT(SSPRT) for track management in MHT. By introducing a hypothesis transition probability, the original track score can increase faster, which solves the first problem. In addition, by setting an independent SSPRT for track deletion, the track score can decrease faster, which solves the second problem. The simulation results show that the proposed SSPRT-based MHT can achieve better tracking performance than MHT based on the WSPRT under a high false alarm spatial density.
基金jointly supported by the National Natural Science Foundation of China(U2067216)Heilongjiang Touyan Team(HITTY-20190033)。
文摘Graphene nanoscrolls with one-dimensional topological structure obtained by Archimedean-type spirals of graphene,inherit the intrinsic properties of the pristine graphene.They have some unique advantages,including open edges/ends,adjustable internal volume,and diameter.Notably,the accommodation of functionalized components in their open interlayer is potentially a fantastic strategy to promote the epoch-making progress in nanotechnology areas,including energy storage,environmental remediation,biotechnology,and smart devices.However,it could destroy the driving forces for the self-rolling of graphene nanosheets and thus it is still a challenge to prepare functionalized graphene nanoscrolls.Here,based on density functional theory prediction,we reported a feasible method to fabricate graphene oxide nanoscrolls with carbon nanotubes as the template.The method was driven by cation-πinteractions,which were caused by metal cations that also acted as the adsorption center.Most importantly,the distinct mechanism and an acidity-dependent rule for the formation of graphene nanoscrolls were identified.Benefiting from the introduced metal cations and the macro three-dimensional hierarchical structure,the produced nanoscroll aerogel exhibited significantly improved adsorption performance toward different organic solvents with the adsorption capacities from 129.9 to 265.7 g g^(−1).This work demonstrates a simple and efficient strategy to fabricate functionalized component-accommodated graphene nanoscroll,which could find important applications in various fields.
