As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase co...As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase conversion that occurs during the charge-discharge process,particularly the deposition of solid Li2S from the liquid-phase polysulfides,which greatly limits its practical application.In this paper,edge-rich MoS2/C hollow microspheres(Edg-MoS2/C HMs)were designed and used to functionalize separator for Li-S battery,resulting in the uniform deposition of Li2S.The microspheres were fabricated through the facile hydrothermal treatment of MoO3-aniline nanowires and a subsequent carbonization process.The obtained Edg-MoS2/C HMs have a strong chemical absorption capability and high density of Li2S binding sites,and exhibit excellent electrocatalytic performance and can effectively hinder the polysulfide shuttle effect and guide the uniform nucleation and growth of Li2S.Furthermore,we demonstrate that the Edg-MoS2/C HMs can effectively regulate the deposition of Li2S and significantly improve the reversibility of the phase conversion of the active sulfur species,especially at high sulfur loadings and high C-rates.As a result,a cell containing a separator functionalized with Edg-MoS2/C HMs exhibited an initial discharge capacity of 935 mAh g-1 at 1.0 C and maintained a capacity of 494 mAh g-1 after 1000 cycles with a sulfur loading of 1.7 mg cm-2.Impressively,at a high sulfur loading of 6.1 mg cm-2 and high rate of 0.5 C,the cell still delivered a high reversible discharge capacity of 478 mAh g-1 after 300 cycles.This work provides fresh insights into energy storage systems related to complex phase conversions.展开更多
Lightweight,flexible,ultrahigh-performance electromagnetic-interfe rence(EMI)shielding materials are urgently required in the areas of aircraft/aerospace,portable and wearable electronics.Herein,1 D carbon nanotubes(C...Lightweight,flexible,ultrahigh-performance electromagnetic-interfe rence(EMI)shielding materials are urgently required in the areas of aircraft/aerospace,portable and wearable electronics.Herein,1 D carbon nanotubes(CNT)and carbon nanofibers(CNF)with 2 D edge-rich graphene(ERG)are used to form a lightweight,flexible CNT-ERG-CNF hybrid foam.This foam was fabricated through a self-sacrificial templating chemical vapor deposition process,where nanocarbons bond through covalent bonding,forming a hierarchical 3 D hybridized carbon nanostructure.Multistage conductive networks and heterogeneous interfaces were constructed using edge-rich nanocarbons to increase the induced currents and interfacial polarization which makes great contributions to achieve high absorption electromagnetic shielding effectiveness(SEA).The CNT-ERG-CNF hybrid foam exhibits EMI shielding effectiveness(SE)exceeding55.4 dB in the X-band while the specific SE(SSE,SE divided by mass density)achieves 9200 dB cm^(3)g^(-1),which surpasses that of nearly all other carbon-based composite materials.Furthermore,the structural stability and durability of the flexible CNT-ERG-CNF hybrid foams is examined by measuring EMI SE after 10000 times cyclic bending.Remarkably,this work not only provides a new idea for preparing hierarchical carbon materials for a wide range of applications,but presents some fundamental insights for achieving higher absorption losses in EMI shielding materials.展开更多
Hydrogen,as a green and clean next-generation fuel,is a key to achieving the goal of carbon neutrality.Constructing an electrocatalyst with bifunctional hydrogen evolution and oxygen evolution activity in the same ele...Hydrogen,as a green and clean next-generation fuel,is a key to achieving the goal of carbon neutrality.Constructing an electrocatalyst with bifunctional hydrogen evolution and oxygen evolution activity in the same electrolyte is a key technology for producing hydrogen via water splitting.Herein,a bimetallic active site catalyst,which possessed an edge-riched MoS_(2)nanoflakes array vertically growing on cubic CoS_(2),forming a nuclear-shell heterogeneous configuration,termed CSC-Mo S_(2)@Co S_(2).was reported The optimal CSC-Mo S_(2)@Co S_(2)-24 possessed good dualfunctional electrocatalytic activity(hydrogen evolution(HER),10 m A·cm^(-2)@241.5 m V and oxygen evolution(OER),10 m A·cm^(-2)@350 m V).Especially,CSC-Mo S_(2)@CoS_(2)-24 exhibited an extremely high mass activity for HER,and only required an overpotential of~550 m V when reaching a large current density of 1422 m A·mg^(-1),which was20.6-fold that of the bulk CoS_(2)(69 m A·mg^(-1)),as well as exhibiting stability of up to 100 h.The good electrocatalytic performance was attributed to the nuclear-shell heterostructure of Mo S_(2)@CoS_(2)hybrid could bring critical synergies,improving efficient mass transfer and electron transfer processes between Co S_(2)and Mo S_(2),which collaboratively promoted the electrocatalytic kinetics.It is foreseeable that the method proposed in this work will have guiding value for the preparation of dual-functional electrocatalysts with multi-interface heterostructures by assembling layered sulfides on cubic sulfides.展开更多
In order to accelerate the reaction kinetics of lithium-sulfur batteries, the introduction of electro catalysis and proper structural control of the sulfur cathode is urgently needed. MoS_(2) nano sheets was selective...In order to accelerate the reaction kinetics of lithium-sulfur batteries, the introduction of electro catalysis and proper structural control of the sulfur cathode is urgently needed. MoS_(2) nano sheets was selectively grown vertically (V-MoS_(2)) on the microwave-reduced graphene (rGO) sheets through chemical coupling to construct a self-supporting sulfur cathode with a nano storage-box structure (V-MoS_(2) as the wall and rGO as the bottom). RGO, which has a high conductivity of 37 S cm^(−1), greatly accelerates the transfer of electrons from the active sites on the edge of the layer to the solution. The introduction of carbon tubes can connect the abundant pores in the foam and act as a long-range conductive path. The 2D-orthogonal-2D structure maximally exposes the edge active sites of MoS_(2), and together with graphene form a nano reactor of sulfur, intermediate lithium polysulfides and discharge product Li_(2)S(2). The effective combination of the microstructure confinement of the nano storage-boxes and the efficient synchronous catalytic mechanism of V-MoS_(2) greatly improves the electrochemical performance of the lithium-sulfur batteries. As a result, the assembled lithium-sulfur battery displays a high initial discharge capacity of 1379 mAh g^(−1), good cycle stability (86% capacity retention after 500 cycles at 0.1C) and superior rate performance.展开更多
基金financially supported by National Natural Science Foundation of China (No. 51672083)Program of Shanghai Academic/Technology Research Leader (18XD1401400)+3 种基金Basic Research Program of Shanghai (17JC1404702)Leading talents in Shanghai in 2018The 111 project (B14018)the Fundamental Research Funds for the Central Universities (222201718002)
文摘As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase conversion that occurs during the charge-discharge process,particularly the deposition of solid Li2S from the liquid-phase polysulfides,which greatly limits its practical application.In this paper,edge-rich MoS2/C hollow microspheres(Edg-MoS2/C HMs)were designed and used to functionalize separator for Li-S battery,resulting in the uniform deposition of Li2S.The microspheres were fabricated through the facile hydrothermal treatment of MoO3-aniline nanowires and a subsequent carbonization process.The obtained Edg-MoS2/C HMs have a strong chemical absorption capability and high density of Li2S binding sites,and exhibit excellent electrocatalytic performance and can effectively hinder the polysulfide shuttle effect and guide the uniform nucleation and growth of Li2S.Furthermore,we demonstrate that the Edg-MoS2/C HMs can effectively regulate the deposition of Li2S and significantly improve the reversibility of the phase conversion of the active sulfur species,especially at high sulfur loadings and high C-rates.As a result,a cell containing a separator functionalized with Edg-MoS2/C HMs exhibited an initial discharge capacity of 935 mAh g-1 at 1.0 C and maintained a capacity of 494 mAh g-1 after 1000 cycles with a sulfur loading of 1.7 mg cm-2.Impressively,at a high sulfur loading of 6.1 mg cm-2 and high rate of 0.5 C,the cell still delivered a high reversible discharge capacity of 478 mAh g-1 after 300 cycles.This work provides fresh insights into energy storage systems related to complex phase conversions.
基金financial supports of this work by National Natural Science Foundation of China(51821091,51872234)Natural Science Basic Research Plan in Shaanxi(No.2020JQ-154)。
文摘Lightweight,flexible,ultrahigh-performance electromagnetic-interfe rence(EMI)shielding materials are urgently required in the areas of aircraft/aerospace,portable and wearable electronics.Herein,1 D carbon nanotubes(CNT)and carbon nanofibers(CNF)with 2 D edge-rich graphene(ERG)are used to form a lightweight,flexible CNT-ERG-CNF hybrid foam.This foam was fabricated through a self-sacrificial templating chemical vapor deposition process,where nanocarbons bond through covalent bonding,forming a hierarchical 3 D hybridized carbon nanostructure.Multistage conductive networks and heterogeneous interfaces were constructed using edge-rich nanocarbons to increase the induced currents and interfacial polarization which makes great contributions to achieve high absorption electromagnetic shielding effectiveness(SEA).The CNT-ERG-CNF hybrid foam exhibits EMI shielding effectiveness(SE)exceeding55.4 dB in the X-band while the specific SE(SSE,SE divided by mass density)achieves 9200 dB cm^(3)g^(-1),which surpasses that of nearly all other carbon-based composite materials.Furthermore,the structural stability and durability of the flexible CNT-ERG-CNF hybrid foams is examined by measuring EMI SE after 10000 times cyclic bending.Remarkably,this work not only provides a new idea for preparing hierarchical carbon materials for a wide range of applications,but presents some fundamental insights for achieving higher absorption losses in EMI shielding materials.
基金financially supported by the National Science Foundation of China(Nos.52203314,52071226 and 51872193)the Natural Science Foundations of Jiangsu Province(No.BK20210847)+1 种基金Jiangsu Key Laboratory for Biomass Energy and Material(No.JSBEM-S-201805)the Natural Science Foundations of the Jiangsu Higher Education Institutions of China(No.21KJB430042)。
文摘Hydrogen,as a green and clean next-generation fuel,is a key to achieving the goal of carbon neutrality.Constructing an electrocatalyst with bifunctional hydrogen evolution and oxygen evolution activity in the same electrolyte is a key technology for producing hydrogen via water splitting.Herein,a bimetallic active site catalyst,which possessed an edge-riched MoS_(2)nanoflakes array vertically growing on cubic CoS_(2),forming a nuclear-shell heterogeneous configuration,termed CSC-Mo S_(2)@Co S_(2).was reported The optimal CSC-Mo S_(2)@Co S_(2)-24 possessed good dualfunctional electrocatalytic activity(hydrogen evolution(HER),10 m A·cm^(-2)@241.5 m V and oxygen evolution(OER),10 m A·cm^(-2)@350 m V).Especially,CSC-Mo S_(2)@CoS_(2)-24 exhibited an extremely high mass activity for HER,and only required an overpotential of~550 m V when reaching a large current density of 1422 m A·mg^(-1),which was20.6-fold that of the bulk CoS_(2)(69 m A·mg^(-1)),as well as exhibiting stability of up to 100 h.The good electrocatalytic performance was attributed to the nuclear-shell heterostructure of Mo S_(2)@CoS_(2)hybrid could bring critical synergies,improving efficient mass transfer and electron transfer processes between Co S_(2)and Mo S_(2),which collaboratively promoted the electrocatalytic kinetics.It is foreseeable that the method proposed in this work will have guiding value for the preparation of dual-functional electrocatalysts with multi-interface heterostructures by assembling layered sulfides on cubic sulfides.
基金the financial supports of the National Natural Science Foundation of China(21875065,51673064)the International Science&Technology Cooperation Program of China(2016YFE0131200)。
文摘In order to accelerate the reaction kinetics of lithium-sulfur batteries, the introduction of electro catalysis and proper structural control of the sulfur cathode is urgently needed. MoS_(2) nano sheets was selectively grown vertically (V-MoS_(2)) on the microwave-reduced graphene (rGO) sheets through chemical coupling to construct a self-supporting sulfur cathode with a nano storage-box structure (V-MoS_(2) as the wall and rGO as the bottom). RGO, which has a high conductivity of 37 S cm^(−1), greatly accelerates the transfer of electrons from the active sites on the edge of the layer to the solution. The introduction of carbon tubes can connect the abundant pores in the foam and act as a long-range conductive path. The 2D-orthogonal-2D structure maximally exposes the edge active sites of MoS_(2), and together with graphene form a nano reactor of sulfur, intermediate lithium polysulfides and discharge product Li_(2)S(2). The effective combination of the microstructure confinement of the nano storage-boxes and the efficient synchronous catalytic mechanism of V-MoS_(2) greatly improves the electrochemical performance of the lithium-sulfur batteries. As a result, the assembled lithium-sulfur battery displays a high initial discharge capacity of 1379 mAh g^(−1), good cycle stability (86% capacity retention after 500 cycles at 0.1C) and superior rate performance.
