Full-spectrum phosphor-converted white-light-emitting diodes(pc-WLED)are emerging as a mainstream technology in semiconductor ***,high-performance blue phosphor which can be excited efficiently by a 400 nm NUV diode c...
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Full-spectrum phosphor-converted white-light-emitting diodes(pc-WLED)are emerging as a mainstream technology in semiconductor ***,high-performance blue phosphor which can be excited efficiently by a 400 nm NUV diode chip is still ***,we present a blue-emitting Na_(3)KMg_(7)(PO_(4))6:Eu^(2+)phosphor synthesized by the solid-reaction ***,we find that the using of Li_(2)CO_(3)as flux can significantly improve the crystal quality and thus the emission efficiency of the ***,the excitation peak of the phosphor shifts from 365 to 400 nm,which is pivotal for efficient NUV(400 nm)diode chip *** practical Eu^(2+)concentration is also enhanced by using Li_(2)CO_(3)as flux,and the absorption efficiency is greatly *** phosphor exhibits superior PL thermal stability,namely retains 94%integrated photoluminescence intensity at 150℃of that at 25℃.As a result,the optimized phosphor shows an emission band peaked at 437 nm with a bandwidth of 40 nm and a high external photoluminescence quantum yield of 51.7%.Finally,a pc-WLED was fabricated by using NKMPO:Eu^(2+)blue,Sr_(2)SiO_(4):Eu^(2+)green,CaAlSiN_(3):Eu^(2+)red phosphors,and a 400 nm NUV diode *** shows a high color rendering index of R_(a)=96.4 and a correlated color temperature of 4358 *** results prove that NKMPO:Eu^(2+)is a promising blue phosphor for full-spectrum WLED based on NUV diode chips.
Lithium-sulfur(Li-S)batteries with high theoretical capacity and energy density need to solve problems such as the high decomposition energy barrier of Li_(2)S and large volume change of sulfur in the charging process...
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Lithium-sulfur(Li-S)batteries with high theoretical capacity and energy density need to solve problems such as the high decomposition energy barrier of Li_(2)S and large volume change of sulfur in the charging process caused by the shuttle effect before practical ***,a green synthesis method is used to prepare polyacrylic acid(PAA)superabsorbent material,and then the pyrolyzed PAA(P/PAA)material is obtained as the positive electrode of Li-S *** functional calculation reveals that the oxygen self-doping pyrolyzed polyacrylic acid(P/PAA)delivered stronger binding energy toward Li2S species in carbonyl C=O than that of graphite powder(GP)which are-1.58 eV and-1.02 eV,*** with the distribution of relaxation time analysis and the in-situ electrochemical impedance approach,it is further demonstrated that the designed P/PAA as sulfur host plays a physical/chemical adsorption dual function in maintaining the stability and rate performance of *** an initial discharge capacity of 1258 mAh/g at 0.1 C and a minimal capacity decline of 0.05%per cycle even after 800 cycles at 0.5 C,the produced cathode demonstrated outstanding electrochemical *** average Coulombic efficiency is nearly 100%.The P/PAA electrodes may typically retain 96%of their capacity while declining on average only 0.033%per cycle after 130 cycles at 3 *** effort provides a new method for the future development of heteroatomic self-doping superabsorbent with promising adsorption properties for polysulfides as cathode materials of Li-S batteries.
The synthesis of active electrode materials at room temperature is one of the effective strategies to reduce the fabrication cost of sodium ion batteries(SIBs).Herein,a layered material(Na_(2)[(VO)_(2)(HPO_(4))_(2)C_(...
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The synthesis of active electrode materials at room temperature is one of the effective strategies to reduce the fabrication cost of sodium ion batteries(SIBs).Herein,a layered material(Na_(2)[(VO)_(2)(HPO_(4))_(2)C_(2)O_(4)]·2H_(2)O,abbreviated as NVPC followingly)with open-framework structures has been successfully prepared at room temperature under ambient conditions and is evaluated as a cathode for *** is revealed that NVPC cathode can deliver a maximum reversible capacity of ca.70 mAh/g at 10 mA/g,and exhibit superior rate capability and cycling performance:at 50 mA/g,maximum reversible capacity ca.50 m Ah/g with capacity retention of 88.4%over 250 cycles corresponds to only 0.046%capacity decay per cycle;at 100 mA/g,a maximum reversible capacity of 35 mAh/g with capacity retention of60.9%over 500 *** study demonstrates a practical example of a low-cost synthesis of the cathode materials for *** the same time,the systematic electrochemical research results also show promising prospects for long lifespan low-cost SIBs.
As the application potential of two-dimensional(2D)materials in fields such as nanoelectronics,optoelectronics,and quantum computing continues to grow,the challenge of fabricating high-quality dielectric layers has be...
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As the application potential of two-dimensional(2D)materials in fields such as nanoelectronics,optoelectronics,and quantum computing continues to grow,the challenge of fabricating high-quality dielectric layers has become crucial to the performance of 2D devices[1],[2].
Hollow structured composite can enhance the structural stability of metal sulfide anode by accommodating its volume variation,while the performance is still hindered by its poor electron/ion ***,we develop a hier-arch...
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Hollow structured composite can enhance the structural stability of metal sulfide anode by accommodating its volume variation,while the performance is still hindered by its poor electron/ion ***,we develop a hier-archical hollow structure to achieve superior electrochemical performance,from which a MOF-to-MOF conversion is utilized to generate hollow Zn-Co_(1-x)S/C composite followed with additional carbon coating *** potassium storage,as-prepared hollow ***/C@C composite displays high capacities of 375 mA h g^(-1)after 100 cycles at 0.2 A g^(-1)and 201 mA h g^(-1)after 500 cycles at 1 A g^(-1).Moreover,it also manifests outstanding rate capability of 200 mA h g^(-1)at 10 A g^(-1),outperforming hollow Co_(1-x)S@C and majority of the reported cobalt-based *** illustration by kinetics analysis and theoretical calculation,both of Zn doping and internal carbon matrix are conductive to promote the charge transportation ability of Co_(1-x)S,thus accounting for the good cycling behavior and excellent rate capacity of hierarchical hollow ***/C@C composite.
Lithium/fluorinated carbon(Li/CF_(x))batteries are greatly limited in their applications mostly due to poor rate *** this study,N,P co-doped biomass carbon was synthesized using melamine and phytic acid as doping sour...
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Lithium/fluorinated carbon(Li/CF_(x))batteries are greatly limited in their applications mostly due to poor rate *** this study,N,P co-doped biomass carbon was synthesized using melamine and phytic acid as doping sources,and the resulting product was then utilized as a precursor for CF_(x).The resulting fluorinated biomass carbon has a high degree of fluorination,exceeding the specific capacity of commercial fluorinated graphite while also demonstrating exceptional performance at high discharge *** the fluorination process,N,P-containing functional groups were removed from the crystalline lattice in the basal *** facilitates the formation of a defect-rich carbon matrix,enhancing the F/C ratio by improving the fluorinated active sites and obtaining more highly active semi-ionic ***,the abundant defects and porous structure promote Li^(+)*** functional theory calculations indicated that doping modification effectively reduces the energy barrier for Li+migration,enhancing Li+transport *** prepared CF_(x)delivers material with a maximum specific capacity of 919 mAh·g^(-1),while maintaining a specific capacity of 702 mAh·g^(-1)at a high discharge current density of 20C(with a capacity retention rate of 76.4%).In this study,fluorinated N,P co-doped biomass carbon,exhibiting ultrahigh capacity and high-rate performance,was prepared for the first time,which can potentially advance the commercialization of CF_(x).
All-inorganic cesium lead halide perovskite nanocrystals(CsPbX_(3),X=Cl,Br,I)have attracted considerable scientific and technological interest due to their precise bandgap tunability,high color purity and efficient **...
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All-inorganic cesium lead halide perovskite nanocrystals(CsPbX_(3),X=Cl,Br,I)have attracted considerable scientific and technological interest due to their precise bandgap tunability,high color purity and efficient ***,their poor stability in harsh conditions such as moisture,ultraviolet(UV)light irradiation and high temperature,is a major obstacle for their further commercial ***,by simply using a new type of precursor,namely“HPbX_(3)”(X=Cl,Br,I),we can achieve the coordination equilibrium for Pb precursors during reaction and obtain high-quality perovskite nanocrystals with tremendously enhanced luminous efficiency and chemical stability based on hot-injection *** prepared a-CsPbb nanocrystals exhibit an extremely high photoluminescence quantum yield of 96%and keep stable in air for more than two months without any post-synthesis ***,stability evaluations under UV light irradiation,water or thermal impact are also performed and the results show substantially improved stability of these nanocrystals as compared with the samples prepared using traditional Pbl_(2) as *** temperature-dependent(10-300 K)steady and transient spectral analysis combined with compositional measurements,it is revealed that the lower structural defect density,which is guaranteed by abundant halogen when using HPbX3 as precursor,is the most important reason for such performance enhancement.
The detrimental“shuttle effect”of lithium polysulfides(LiPSs)together with sluggish multi-order reaction kinetics are the main drawbacks hindering lithium-sulfur(Li-S)batteries from commercial ***,we first propose t...
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The detrimental“shuttle effect”of lithium polysulfides(LiPSs)together with sluggish multi-order reaction kinetics are the main drawbacks hindering lithium-sulfur(Li-S)batteries from commercial ***,we first propose the implementability of layered rare-earth hydroxides(LREHs)in Li-S batteries to optimize electrochemical *** this work,a two-dimensional(2D)rare-earth-based composite constructed by the layered gadolinium hydroxy chloride[Gd_(2)(OH)_(5)(H_(2)O)_(n)]Cl nanoplates(LGdH NPs)and graphene oxide(GO)was designed as a sulfur immobilizer for Li-S *** the experimental results and density functional theory(DFT)calculations,it is revealed that the LGdH@GO composite not only provides a strong anchoring of the intermediates during cycling,but also acts as an effective catalyst to accelerate the liquid-solid conversion of *** Li-S batteries assembled by LGdH@GO modified separators delivered a superior rate performance with a specific capacity of 605.34 mAh/g at 5 C,as well as excellent cycle stability with a decay rate of 0.087%over 500 cycles at 2 *** study provided a deep understanding of the mechanism to suppress the“shuttle effect”by the LREHs,and a guide to design effective functional interlayers for high-performance Li-S batteries with excellent electrocatalytic activity.
Covalent organic frameworks(COFs)are an emerging class for solid-state electrolytes due to their ordered and customizable ion transport *** high ionic conductivity(σ_(Li+))and Li^(+) transference number(t_(Li+))are a...
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Covalent organic frameworks(COFs)are an emerging class for solid-state electrolytes due to their ordered and customizable ion transport *** high ionic conductivity(σ_(Li+))and Li^(+) transference number(t_(Li+))are achieved;the high-arealcapacity solid-state lithium metal battery(LMB)still encountered challenges;which is mainly determined by homogeneous Li^(+) flux through channels and ***;we design a COF coupling anionic skeletons with branched ion-conductive chains(COF-S)as tailored fast ion-transport channels to achieve high-areal-capacity solid-state *** the dispersed COF-S-based electrolyte is further obtained by incorporating ethoxylated trimethylolpropane triacrylate(ETPTA)and Li FSI(ETPTA-COF-S)via in situ light *** this way;the abundant SO_(3)-groups promote Li+adsorption and facilitate axial transport via 1D channels;thus enabling highσLi+of 1.29 m S cm^(-1)and tLi+of *** branched chains can tailor ion channels to suppress largesize anions transport;disperse and uniform Li+flux;thus leading to high average Coulombic efficiency(CE)up to 98.43%for 100 cycles(~800 h)at 0.5 m A cm^(-2)under the high areal capacity of 2 mAh cm^(-2).When paired with 2 m Ah cm^(-2)LiFePO_(4)(LFP)cathode and thin Li anode of 20μm;Li||ETPTA-COF-S||LFP exhibits superior cyclic stability for 80 cycles.
Low-cost and high-energy-density manganese-based compounds are promising cathode materials for rechargeable aqueous zinc-ion batteries(AZIBs),however,they often experience cycling instability issues and inferior rate ...
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Low-cost and high-energy-density manganese-based compounds are promising cathode materials for rechargeable aqueous zinc-ion batteries(AZIBs),however,they often experience cycling instability issues and inferior rate ***,we report a new layered manganese-based cathode material,ZnMn_(3)O_(7)(ZMO),which possesses a large interlayer spacing of 4.8Åand allows the intercalation of~1.23 Zn-ions per formula unit(corresponding to a capacity of~170 mAh/g).Importantly,ZMO exhibits good cycling stability(72.9%capacity retention over 400 cycles),ultrafast-charging capability(73%state of charge in 1.5 min),and an ultrahigh power density(3510 W/kg at 88 Wh/kg).Through kinetic characterization,the favorable diffusion of ions and the dominant capacitor contribution are found to be conducive to the achievement of superior fast charging ***,the charge storage mechanism is revealed by ex-situ XRD and ex-situ *** work may shed light on the design of high-performance electrode materials for AZIBs.
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