It has been well known that doping nano-scale catalysts can significantly improve both the kinetics and reversible hydrogen storage capacity of MgH_(2) . However, so far it is still a challenge to directly synthesize ...It has been well known that doping nano-scale catalysts can significantly improve both the kinetics and reversible hydrogen storage capacity of MgH_(2) . However, so far it is still a challenge to directly synthesize ultrafine catalysts(e.g., < 5 nm), mainly because of the complicated chemical reaction processes. Here, a facile one-step high-energy ball milling process is developed to in situ form ultrafine Ni nanoparticles from the nickel acetylacetonate precursor in the MgH_(2) matrix. With the combined action of ultrafine metallic Ni and expanded graphite(EG), the formed MgH_(2)-Ni-EG nanocomposite with the optimized doping amounts of Ni and EG can still release 7.03 wt.% H_(2) within 8.5 min at 300 ℃ after 10 cycles. At a temperature close to room temperature(50 ℃), it can also absorb 2.42 wt.% H_(2) within 1 h. It can be confirmed from the microstructural characterization analysis that the in situ formed ultrafine metallic Ni is transformed into Mg_(2)Ni/Mg_(2)NiH_4 in the subsequent hydrogen absorption and desorption cycles. It is calculated that the dehydrogenation activation energy of the MgH_(2)-Ni-EG nanocomposite is also reduced obviously in comparison with the pure MgH_(2) . Our work provides a methodology to significantly improve the hydrogen storage performance of MgH_(2) by combining the in situ formed and uniformly dispersed ultrafine metallic catalyst from the precursor and EG.展开更多
LiBH_(4) has been considered as one of the most promising energy storage materials with its ultrahigh hydrogen capacity,which can supply hydrogen through hydrolysis process or realize hydrogen-to-electricity conversio...LiBH_(4) has been considered as one of the most promising energy storage materials with its ultrahigh hydrogen capacity,which can supply hydrogen through hydrolysis process or realize hydrogen-to-electricity conversion via anodic oxidation reaction of direct borohydride fuel cells(DBFCs).However,the realization of practical hydrogen applications heavily depends on the effective synthesis of high-purity LiBH_(4) and recycling of the spent fuels(LiBO_(2)·xH_(2)O).The present work demonstrates a convenient and high-efficiency solvent-free strategy for regenerating LiBH_(4) with a maximum yield close to 80%,by retrieving its by-products with MgH_(2) as a reducing agent under ambient conditions.Besides,the hydrogen released from the regeneration course can completely compensate the demand for consumed MgH_(2).The isotopic tracer method reveals that the hydrogen stored in LiBH_(4) comes from both MgH_(2) and coordinated water bound to LiBO_(2).Here,the expensive MgH_(2) can be substituted with the readily available and cost-effective MgH_(2)-Mg mixtures to simplify the regeneration route.Notably,LiBH_(4) catalyzed by CoCl_(2) can stably supply hydrogen to proton exchange membrane fuel cell(PEMFC),thus powering a portable prototype vehicle.By combining hydrogen storage,production and utilization in a closed cycle,this work offers new insights into deploying boron-based hydrides for energy applications.展开更多
O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on...O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.展开更多
An optimized low-temperature chromizing process at 500℃ was realized on a plain medium-carbon steel with 0.45 wt pct carbon via a duplex chromizing process which consists of a precursor plasma nitriding, and a follow...An optimized low-temperature chromizing process at 500℃ was realized on a plain medium-carbon steel with 0.45 wt pct carbon via a duplex chromizing process which consists of a precursor plasma nitriding, and a followed salt bath thermoreactive deposition and diffusion （TRD） chromizing process. CrN layer with a thin diffusion layer underneath was formed. The duplex chromizing process was studied by optical microscopy （OM）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS）, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. It was found that the chromizing speed at 500℃ was successfully enhanced by adding more Cr-Fe powders into the salt bath, and the CrN layer formed at the cost of the prior nitride compound layer. A CrN layer with average 8.1/~m in thickness and 1382 HV0.01 in microhardness was formed on the substrate by duplex chromizing at 500℃ for 24 h. Further more, the CrN layer consisted of nanocrystalline CrN grains.展开更多
SnS with high theoretical capacity is a promising anode material for lithiumion batteries.However,dramatic volume changes of SnS during repeated discharge/charge cycles result in fractures or even pulverization of ele...SnS with high theoretical capacity is a promising anode material for lithiumion batteries.However,dramatic volume changes of SnS during repeated discharge/charge cycles result in fractures or even pulverization of electrode,leading to rapid capacity degradation.To solve this problem,we construct a dual-carbon-confined SnS nanostructure(denoted as SnS@C/rGO)by depositing semi-graphitized carbon layers on reduced graphene oxide(rGO)supported SnS nanoplates during high-temperature reduction.The dual carbon of rGO and in situ formed carbon coating confines growth of SnS during the high-temperature calcination.Moreover,during the reversible Li+storage the dual-carbon modification enables good electronic conductivity,relieves the volume effect,and provides double insurance for the electrical contact of SnS even after repeated cycles.Benefiting from the dual-carbon confinement,SnS@C/rGO exhibits significantly enhanced rate capability and cycling stability compared with the bare and single carbon modified SnS.SnS@C/rGO presents reversible capacity of 1029.8 mAh g^(-1)at 0.2 A g^(-1).Even at a high current density of 1 A g^(-1),it initially delivers reversible capacity of 934.0 mAh g^(-1)and retains 98.2%of the capacity(918.0 mAh g^(-1))after 330 cycles.This work demonstrates potential application of dual-carbon modification in the development of electrode materials for high-performance lithium-ion batteries.展开更多
Hydrolysis of Mg-based materials is considered as a potential means of safe and convenient real-time control of H_(2)release,enabling efficient loading,discharge and utilization of hydrogen in portable electronic devi...Hydrolysis of Mg-based materials is considered as a potential means of safe and convenient real-time control of H_(2)release,enabling efficient loading,discharge and utilization of hydrogen in portable electronic devices.At present work,the hydrogen generation properties of MgLi-graphite composites were evaluated for the first time.The MgLi-graphite composites with different doping amounts of expanded graphite(abbreviated as EG hereinafter)were synthesized through ball milling and the hydrogen behaviors of the composites were investigated in chloride solutions.Among the above doping systems,the 10 wt.%EG-doped MgLi exhibited the best hydrogen performance in MgCl_(2)solutions.In particular,the 22 h-milled MgLi-10 wt.%EG composites possessed both desirable hydrogen conversion and rapid reaction kinetics,delivering a hydrogen yield of 966 mL H_(2)g^(-1)within merely 2 min and a maximum hydrogen generation rate of 1147 mL H_(2)min^(-1)g^(-1),as opposed to the sluggish kinetics in the EG-free composites.Moreover,the EG-doped MgLi showed superior air-stable ability even under a 75 RH%ambient atmosphere.For example,the 22 h-milled MgLi-10 wt.%EG composites held a fuel conversion of 89%after air exposure for 72 h,rendering it an advantage for Mg-based materials to safely store and transfer in practical applications.The similar favorable hydrogen performance of MgLi-EG composites in(simulate)seawater may shed light on future development of hydrogen generation technologies.展开更多
To develop anode materials with superior volumetric storage is crucial for practical application of lithium/sodium-ion batteries.Here,we have developed a micro/nanostructured Sn S/few-layer graphene(Sn S/FLG)composite...To develop anode materials with superior volumetric storage is crucial for practical application of lithium/sodium-ion batteries.Here,we have developed a micro/nanostructured Sn S/few-layer graphene(Sn S/FLG)composite by facile scalable plasma milling.Inside the hybrid,SnS nanoparticles are tightly supported by FLG,forming nanosized primary particles as building blocks and assembling to microsized secondary granules.With this unique micro/nanostructure,the Sn S/FLG composite possesses a high tap density of 1.98 g cm^(-3)and thus ensures a high volumetric storage.The combination of Sn S nanoparticles and FLG nanosheets can not only enhance the overall electrical conductivity and facilitate the ion diffusion greatly,but alleviate the large volume expansion of Sn S effectively and maintain the electrode integrity during cycling.Thus,the densely compacted Sn S/FLG composite exhibits superior volumetric lithium and sodium storage,including high volumetric capacities of 1926.5/1051.4 m Ah cm^(-3)at 0.2 A g^(-1),and high retained capacities of 1754.3/760.3 m Ah cm^(-3)after 500cycles at 1.0 A g^(-1).With superior volumetric storage performance and facile scalable synthesis,the Sn S/FLG composite can be a promising anode for practical batteries application.展开更多
Rare earth-based superlattice alloys have great potential for gaseous hydrogen storage,as well as successful application as nickel-metal hydride batteries anodes.In this work,Y substitution was carried out to adjust t...Rare earth-based superlattice alloys have great potential for gaseous hydrogen storage,as well as successful application as nickel-metal hydride batteries anodes.In this work,Y substitution was carried out to adjust the gaseous hydrogen storage properties of A_(2)B_(7)-type La_(0.7)Mg_(0.3)Ni_(3.5)alloys.The results indicate a multiphase structure in the alloys comprised of the main rhombohedral Gd_(2)Co_(7)and PuNi_(3)phases,with a small amount of CaCu_(5)phase.Moreover,the Y substitution results in higher abundance of the Gd_(2)Co_(7)phase.The alloy La_(0.42)Y_(0.28)Mg_(0.3)Ni_(3.5)exhibits a hydrogen storage cap acity of 1.55 wt%at 298 K and a desorption plateau pressure of 0.244 MPa.In addition,this alloy demonstrates a stable cycle life by a capacity retention of 94.2%after 50 cycles,with the main capacity degradation occurring during the initial 20 cycles.This work accentuates the potential of the La-Y-Mg-Ni-based superlattice alloys for applications in solid-state hydrogen storage.展开更多
MgH_(2),as one of the typical solid-state hydrogen storage materials,has attracted extensive attention.However,the slow kinetics and poor cycle stability limit its application.In this work,LiBH_(4) and YNi_(5) alloy w...MgH_(2),as one of the typical solid-state hydrogen storage materials,has attracted extensive attention.However,the slow kinetics and poor cycle stability limit its application.In this work,LiBH_(4) and YNi_(5) alloy were co-added as additives to MgH_(2) via ball milling,thereby realizing an excellent dehydrogenation per-formance and good cycle stability at 300 ℃.The MgH_(2)-0.04LiBH_(4)-0.01YNi_(5) composite can release 7 wt.%of hydrogen in around 10 min at 300 ℃ and still have a reversible hydrogen storage capacity of 6.42 wt.%after 110 cycles,with a capacity retention rate as high as 90.3%based on the second dehydrogenation capacity.The FTIR results show that LiBH_(4) can reversibly absorb and desorb hydrogen throughout the hydrogen ab/desorption process,which contributes a portion of the reversible hydrogen storage capacity to the MgH_(2)-0.04LiBH_(4)-0.01YNi_(5) composite.Due to the small amount of LiBH_(4) and YNi_(5),the dehydro-genation activation energy of MgH_(2) did not decrease significantly,nor did the dehydrogenation enthalpy(△H)change.However,the MgNi3B2 and in-situ formed YH3 during the hydrogen absorption/desorption cycles is not only beneficial to the improvement of the kinetics performance for MgH_(2) but also improves its cycle stability.This work provides a straightforward method for developing high reversible hydrogen capacity on Mg-based hydrogen storage materials with moderate kinetic performance.展开更多
RM_(3) compounds(R=rare earth metals,M=transition metals)have rarely been studied for gaseous hydrogen storage applications because of unfavorable thermodynamics.In this work,the hydrogen storage properties of a singl...RM_(3) compounds(R=rare earth metals,M=transition metals)have rarely been studied for gaseous hydrogen storage applications because of unfavorable thermodynamics.In this work,the hydrogen storage properties of a single-phase YFe_(3)alloy were improved by non-stoichiometric composition and alloying with Sc and Zr.Only the Y_(1.1-y)Sc_(y)Fe_(3)(y=0.22,0.33)alloys consist of a single rhombohedral phase.The Sc substitution for Y leads to the reduction in the unit cell volume of the YFe_(3)phase,and thus significantly increases the dehydriding equilibrium pressure and decreases the dehydrogenation temperature.The alloy Y_(0.77)Sc_(0.33)Fe_(3)delivers a decomposition enthalpy change of 33.54 kJ/mol and a lowest dehydrogenation temperature of 135℃,in comparison with 38.99 kJ/mol and 165℃ for the alloy Y_(1.1)Fe_(3).The Zr substitution causes a similar thermodynamic destabilization effect,but the composition and microstructure of Y-Zr-Fe alloys need to be further optimized.展开更多
Sphere-shape Eu（DBM）3Phen@Si02 nanoparticles were fabricated by employing a modified alkaline catalyzed hydrolysis and precipitation method. The silica coated on the particles surface was obtained by means of hydrol...Sphere-shape Eu（DBM）3Phen@Si02 nanoparticles were fabricated by employing a modified alkaline catalyzed hydrolysis and precipitation method. The silica coated on the particles surface was obtained by means of hydrolysis and condensation of tetraethyl orthosilicate （TEOS）. In this study, the particles morphology was analyzed by scanning electron microscopy （SEM） and the surface composition of samples was characterized by X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）. It is confirmed that the Si02 shell has been coated on the rare earth complexes successfully. Moreover, the near-infrared photoluminescence emission analysis on the nanoparticles showed that the SiO2 shell would increase the luminescence intensity of Eu（DBM）3Phen. This is primarily due to the reason that SiO2 shell with chemical inertness can effectively reduce the ion Eu3~ non-radiation transition probabilities, as well as the probability of rare earth luminescence quenching caused by the external medium.展开更多
Sn-based chalcogenides are considered as one of the most promising anode materials for lithium-ion batteries(LIBs)because of their high capacities through both conversion and alloying reactions.However,the realization...Sn-based chalcogenides are considered as one of the most promising anode materials for lithium-ion batteries(LIBs)because of their high capacities through both conversion and alloying reactions.However,the realization of full capacities of Sn-based chalcogenides is mainly hindered by the large volume variation and inferior reversibility of conversion reaction during cycling.In present work,a new ternary Sn SMo-graphene nanosheets(Sn S-Mo-GNs)composite is fabricated by a simple and scalable plasma milling method,in which Sn S nanoparticles are tightly bonded with Mo and GNs.The Mo and GNs additives can effectively alleviate the large volume change of Sn S upon cycling,which leads to a stable electrochemical framework.Moreover,they can significantly suppress the Sn agglomeration in lithiated Sn S,which enables highly reversible conversion reaction during cycling.As anode for LIBs,the Sn S-Mo-GNs composite exhibits a high initial coulombic efficiency of 86.9%(almost complete reversibility of Sn S,~97.3%),high cyclic coulombic efficiency after initial three cycles(>99.5%),and long lifespan(up to 600 cycles).Moreover,it also demonstrates superior electrochemical performance for sodium storage.Thus,this work demonstrates a potential anode for batteries application and provides a viable strategy to obtain highly reversible and stable anodes for lithium/sodium storage.展开更多
基金financial support from the National Basic Research Program of China (2018YFB1502100)the support from the PolyU grant (No.G-YW5N)。
文摘It has been well known that doping nano-scale catalysts can significantly improve both the kinetics and reversible hydrogen storage capacity of MgH_(2) . However, so far it is still a challenge to directly synthesize ultrafine catalysts(e.g., < 5 nm), mainly because of the complicated chemical reaction processes. Here, a facile one-step high-energy ball milling process is developed to in situ form ultrafine Ni nanoparticles from the nickel acetylacetonate precursor in the MgH_(2) matrix. With the combined action of ultrafine metallic Ni and expanded graphite(EG), the formed MgH_(2)-Ni-EG nanocomposite with the optimized doping amounts of Ni and EG can still release 7.03 wt.% H_(2) within 8.5 min at 300 ℃ after 10 cycles. At a temperature close to room temperature(50 ℃), it can also absorb 2.42 wt.% H_(2) within 1 h. It can be confirmed from the microstructural characterization analysis that the in situ formed ultrafine metallic Ni is transformed into Mg_(2)Ni/Mg_(2)NiH_4 in the subsequent hydrogen absorption and desorption cycles. It is calculated that the dehydrogenation activation energy of the MgH_(2)-Ni-EG nanocomposite is also reduced obviously in comparison with the pure MgH_(2) . Our work provides a methodology to significantly improve the hydrogen storage performance of MgH_(2) by combining the in situ formed and uniformly dispersed ultrafine metallic catalyst from the precursor and EG.
基金This work was financially supported by the National Natural Science Foundation of China Projects(Nos.51771075)the National Key R&D Program of China(No.2018YFB1502101)+2 种基金the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.NSFC51621001)by the Project Supported by Nat-ural Science Foundation of Guangdong Province of China(2016A030312011)Shao acknowledges support from Macao Science and Technology Development Fund(FDCT)(Project No.:0062/2018/A2 and 0019/2019/AGJ).
文摘LiBH_(4) has been considered as one of the most promising energy storage materials with its ultrahigh hydrogen capacity,which can supply hydrogen through hydrolysis process or realize hydrogen-to-electricity conversion via anodic oxidation reaction of direct borohydride fuel cells(DBFCs).However,the realization of practical hydrogen applications heavily depends on the effective synthesis of high-purity LiBH_(4) and recycling of the spent fuels(LiBO_(2)·xH_(2)O).The present work demonstrates a convenient and high-efficiency solvent-free strategy for regenerating LiBH_(4) with a maximum yield close to 80%,by retrieving its by-products with MgH_(2) as a reducing agent under ambient conditions.Besides,the hydrogen released from the regeneration course can completely compensate the demand for consumed MgH_(2).The isotopic tracer method reveals that the hydrogen stored in LiBH_(4) comes from both MgH_(2) and coordinated water bound to LiBO_(2).Here,the expensive MgH_(2) can be substituted with the readily available and cost-effective MgH_(2)-Mg mixtures to simplify the regeneration route.Notably,LiBH_(4) catalyzed by CoCl_(2) can stably supply hydrogen to proton exchange membrane fuel cell(PEMFC),thus powering a portable prototype vehicle.By combining hydrogen storage,production and utilization in a closed cycle,this work offers new insights into deploying boron-based hydrides for energy applications.
基金financial support from the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No. NSFC51621001)the Guangdong Special Support Program (2017TQ04N224)+1 种基金the Guangdong Natural Science Funds for Distinguished Young Scholar (Grant No. 2017B030306004)the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme。
文摘O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.
基金This work was financially supported by the National Natural Science Foundation of China(Granted No.50671038).
文摘An optimized low-temperature chromizing process at 500℃ was realized on a plain medium-carbon steel with 0.45 wt pct carbon via a duplex chromizing process which consists of a precursor plasma nitriding, and a followed salt bath thermoreactive deposition and diffusion （TRD） chromizing process. CrN layer with a thin diffusion layer underneath was formed. The duplex chromizing process was studied by optical microscopy （OM）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS）, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. It was found that the chromizing speed at 500℃ was successfully enhanced by adding more Cr-Fe powders into the salt bath, and the CrN layer formed at the cost of the prior nitride compound layer. A CrN layer with average 8.1/~m in thickness and 1382 HV0.01 in microhardness was formed on the substrate by duplex chromizing at 500℃ for 24 h. Further more, the CrN layer consisted of nanocrystalline CrN grains.
基金the financial support from the Guangdong Natural Science Funds for Distinguished Young Scholar(Grant No.2017B030306004)Guangdong Special Support Program(2017TQ04N224)+2 种基金National Natural Science Foundation of China(Grant No.51671089)the support from the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(NSFC51621001)Guangdong Province Universities and Col eges Pearl River Scholar Funded Scheme
文摘SnS with high theoretical capacity is a promising anode material for lithiumion batteries.However,dramatic volume changes of SnS during repeated discharge/charge cycles result in fractures or even pulverization of electrode,leading to rapid capacity degradation.To solve this problem,we construct a dual-carbon-confined SnS nanostructure(denoted as SnS@C/rGO)by depositing semi-graphitized carbon layers on reduced graphene oxide(rGO)supported SnS nanoplates during high-temperature reduction.The dual carbon of rGO and in situ formed carbon coating confines growth of SnS during the high-temperature calcination.Moreover,during the reversible Li+storage the dual-carbon modification enables good electronic conductivity,relieves the volume effect,and provides double insurance for the electrical contact of SnS even after repeated cycles.Benefiting from the dual-carbon confinement,SnS@C/rGO exhibits significantly enhanced rate capability and cycling stability compared with the bare and single carbon modified SnS.SnS@C/rGO presents reversible capacity of 1029.8 mAh g^(-1)at 0.2 A g^(-1).Even at a high current density of 1 A g^(-1),it initially delivers reversible capacity of 934.0 mAh g^(-1)and retains 98.2%of the capacity(918.0 mAh g^(-1))after 330 cycles.This work demonstrates potential application of dual-carbon modification in the development of electrode materials for high-performance lithium-ion batteries.
基金financially supported by the National Natural Science Foundation of China Projects(Nos.51771075)the National Key R&D Program of China(No.2018YFB1502101)+1 种基金the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.NSFC51621001)the Project Supported by Natural Science Foundation of Guangdong Province of China(2016A030312011)
文摘Hydrolysis of Mg-based materials is considered as a potential means of safe and convenient real-time control of H_(2)release,enabling efficient loading,discharge and utilization of hydrogen in portable electronic devices.At present work,the hydrogen generation properties of MgLi-graphite composites were evaluated for the first time.The MgLi-graphite composites with different doping amounts of expanded graphite(abbreviated as EG hereinafter)were synthesized through ball milling and the hydrogen behaviors of the composites were investigated in chloride solutions.Among the above doping systems,the 10 wt.%EG-doped MgLi exhibited the best hydrogen performance in MgCl_(2)solutions.In particular,the 22 h-milled MgLi-10 wt.%EG composites possessed both desirable hydrogen conversion and rapid reaction kinetics,delivering a hydrogen yield of 966 mL H_(2)g^(-1)within merely 2 min and a maximum hydrogen generation rate of 1147 mL H_(2)min^(-1)g^(-1),as opposed to the sluggish kinetics in the EG-free composites.Moreover,the EG-doped MgLi showed superior air-stable ability even under a 75 RH%ambient atmosphere.For example,the 22 h-milled MgLi-10 wt.%EG composites held a fuel conversion of 89%after air exposure for 72 h,rendering it an advantage for Mg-based materials to safely store and transfer in practical applications.The similar favorable hydrogen performance of MgLi-EG composites in(simulate)seawater may shed light on future development of hydrogen generation technologies.
基金the financial support from the Innovative Research Groups of the National Natural Science Foundation of China(No.51621001)National Natural Science Foundation of China(No.51671088,51671089)
文摘To develop anode materials with superior volumetric storage is crucial for practical application of lithium/sodium-ion batteries.Here,we have developed a micro/nanostructured Sn S/few-layer graphene(Sn S/FLG)composite by facile scalable plasma milling.Inside the hybrid,SnS nanoparticles are tightly supported by FLG,forming nanosized primary particles as building blocks and assembling to microsized secondary granules.With this unique micro/nanostructure,the Sn S/FLG composite possesses a high tap density of 1.98 g cm^(-3)and thus ensures a high volumetric storage.The combination of Sn S nanoparticles and FLG nanosheets can not only enhance the overall electrical conductivity and facilitate the ion diffusion greatly,but alleviate the large volume expansion of Sn S effectively and maintain the electrode integrity during cycling.Thus,the densely compacted Sn S/FLG composite exhibits superior volumetric lithium and sodium storage,including high volumetric capacities of 1926.5/1051.4 m Ah cm^(-3)at 0.2 A g^(-1),and high retained capacities of 1754.3/760.3 m Ah cm^(-3)after 500cycles at 1.0 A g^(-1).With superior volumetric storage performance and facile scalable synthesis,the Sn S/FLG composite can be a promising anode for practical batteries application.
基金Project supported by the National Natural Science Foundation of China(52271214,51831009)。
文摘Rare earth-based superlattice alloys have great potential for gaseous hydrogen storage,as well as successful application as nickel-metal hydride batteries anodes.In this work,Y substitution was carried out to adjust the gaseous hydrogen storage properties of A_(2)B_(7)-type La_(0.7)Mg_(0.3)Ni_(3.5)alloys.The results indicate a multiphase structure in the alloys comprised of the main rhombohedral Gd_(2)Co_(7)and PuNi_(3)phases,with a small amount of CaCu_(5)phase.Moreover,the Y substitution results in higher abundance of the Gd_(2)Co_(7)phase.The alloy La_(0.42)Y_(0.28)Mg_(0.3)Ni_(3.5)exhibits a hydrogen storage cap acity of 1.55 wt%at 298 K and a desorption plateau pressure of 0.244 MPa.In addition,this alloy demonstrates a stable cycle life by a capacity retention of 94.2%after 50 cycles,with the main capacity degradation occurring during the initial 20 cycles.This work accentuates the potential of the La-Y-Mg-Ni-based superlattice alloys for applications in solid-state hydrogen storage.
基金National Natural Science Foundation of China(Nos.52271213 and 52271221).
文摘MgH_(2),as one of the typical solid-state hydrogen storage materials,has attracted extensive attention.However,the slow kinetics and poor cycle stability limit its application.In this work,LiBH_(4) and YNi_(5) alloy were co-added as additives to MgH_(2) via ball milling,thereby realizing an excellent dehydrogenation per-formance and good cycle stability at 300 ℃.The MgH_(2)-0.04LiBH_(4)-0.01YNi_(5) composite can release 7 wt.%of hydrogen in around 10 min at 300 ℃ and still have a reversible hydrogen storage capacity of 6.42 wt.%after 110 cycles,with a capacity retention rate as high as 90.3%based on the second dehydrogenation capacity.The FTIR results show that LiBH_(4) can reversibly absorb and desorb hydrogen throughout the hydrogen ab/desorption process,which contributes a portion of the reversible hydrogen storage capacity to the MgH_(2)-0.04LiBH_(4)-0.01YNi_(5) composite.Due to the small amount of LiBH_(4) and YNi_(5),the dehydro-genation activation energy of MgH_(2) did not decrease significantly,nor did the dehydrogenation enthalpy(△H)change.However,the MgNi3B2 and in-situ formed YH3 during the hydrogen absorption/desorption cycles is not only beneficial to the improvement of the kinetics performance for MgH_(2) but also improves its cycle stability.This work provides a straightforward method for developing high reversible hydrogen capacity on Mg-based hydrogen storage materials with moderate kinetic performance.
基金Project supported by the National Key R&D Program of China(2019YFB1505101)the National Natural Science Foundation of China(U1601212,51901080)the Natural Science Foundation of Guangdong Province(2016A030312011)。
文摘RM_(3) compounds(R=rare earth metals,M=transition metals)have rarely been studied for gaseous hydrogen storage applications because of unfavorable thermodynamics.In this work,the hydrogen storage properties of a single-phase YFe_(3)alloy were improved by non-stoichiometric composition and alloying with Sc and Zr.Only the Y_(1.1-y)Sc_(y)Fe_(3)(y=0.22,0.33)alloys consist of a single rhombohedral phase.The Sc substitution for Y leads to the reduction in the unit cell volume of the YFe_(3)phase,and thus significantly increases the dehydriding equilibrium pressure and decreases the dehydrogenation temperature.The alloy Y_(0.77)Sc_(0.33)Fe_(3)delivers a decomposition enthalpy change of 33.54 kJ/mol and a lowest dehydrogenation temperature of 135℃,in comparison with 38.99 kJ/mol and 165℃ for the alloy Y_(1.1)Fe_(3).The Zr substitution causes a similar thermodynamic destabilization effect,but the composition and microstructure of Y-Zr-Fe alloys need to be further optimized.
基金financial support from the National Natural Science Foundation of China (No. 60972134, No. 51205137)the Fundamental Research Funds for the Central Universities with grant no. 2012ZM0067
文摘Sphere-shape Eu（DBM）3Phen@Si02 nanoparticles were fabricated by employing a modified alkaline catalyzed hydrolysis and precipitation method. The silica coated on the particles surface was obtained by means of hydrolysis and condensation of tetraethyl orthosilicate （TEOS）. In this study, the particles morphology was analyzed by scanning electron microscopy （SEM） and the surface composition of samples was characterized by X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）. It is confirmed that the Si02 shell has been coated on the rare earth complexes successfully. Moreover, the near-infrared photoluminescence emission analysis on the nanoparticles showed that the SiO2 shell would increase the luminescence intensity of Eu（DBM）3Phen. This is primarily due to the reason that SiO2 shell with chemical inertness can effectively reduce the ion Eu3~ non-radiation transition probabilities, as well as the probability of rare earth luminescence quenching caused by the external medium.
基金the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Nos.51621001,51671088 and 51671089)。
文摘Sn-based chalcogenides are considered as one of the most promising anode materials for lithium-ion batteries(LIBs)because of their high capacities through both conversion and alloying reactions.However,the realization of full capacities of Sn-based chalcogenides is mainly hindered by the large volume variation and inferior reversibility of conversion reaction during cycling.In present work,a new ternary Sn SMo-graphene nanosheets(Sn S-Mo-GNs)composite is fabricated by a simple and scalable plasma milling method,in which Sn S nanoparticles are tightly bonded with Mo and GNs.The Mo and GNs additives can effectively alleviate the large volume change of Sn S upon cycling,which leads to a stable electrochemical framework.Moreover,they can significantly suppress the Sn agglomeration in lithiated Sn S,which enables highly reversible conversion reaction during cycling.As anode for LIBs,the Sn S-Mo-GNs composite exhibits a high initial coulombic efficiency of 86.9%(almost complete reversibility of Sn S,~97.3%),high cyclic coulombic efficiency after initial three cycles(>99.5%),and long lifespan(up to 600 cycles).Moreover,it also demonstrates superior electrochemical performance for sodium storage.Thus,this work demonstrates a potential anode for batteries application and provides a viable strategy to obtain highly reversible and stable anodes for lithium/sodium storage.
