查看更多>>摘要：Silicon(Si)has mild discharge potential and high theoretical capacity,making it a highly desirable material for lithium-ion batteries(LIBs).Nevertheless,the excessive volume expansion,poor ion/electron conductiv-ity and unstable solid electrolyte interface(SEI)hinder practical application to LIBs.Herein,the metallic antimony(Sb)stabilized porous Si(Si-Sb)composite was prepared by magnesiothermic reduction of Sb2O3 and Mg2Si and chemical etching to remove the by-product of MgO.The highly conductive Sb nanodots embedded in the Si liga-ments promote not only the formation of conductive and stable LiF-rich SEI,but also the electron/ion transport ability of Si.Owing to the outstanding bulk/interface stability,excellent conductivity,as well as ideal porous structure,the Si-Sb electrode demonstrates a capacity of 820 mAh·g-1 after undergoing 320 turns at 1000 mA·g-1.Additionally,it exhibits a stable capacity of 675 mAh·g-1 when tested at a higher current density of 5000 mA·g-1.The results reveal a viable solution to solve three problems at the same time,namely the poor conductivity,inferior SEI and excessive volume expansion of Si,boding well for the design of Si-based materials for high-energy LIBs.
查看更多>>摘要：The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries(PIBs),resulting in comparatively poor rate performance and cycle stability.Herein,we report a high-rate performance and cycling stability amorphous carbon electrode achieved through nitrogen and phosphorous co-doping.The as-prepared N,P co-doped carbon electrodes have distinct 3D structures with large surface areas,hierarchical pore architectures,and increased interlayer spaces resulting from the direct pyrolysis of supramolecular self-assembled aggregates without tem-plates.The obtained electrode N3P1 exhibits a reversible specific capacity of 258 mAh·g-1 at a current density of 0.1 A·g-1 and a good long-term cycle performance(96.1％capacity retention after 800 cycles at 0.5 A-g-1).Kinetic investigations show that the N3P1 electrode with the well-developed porous structure and large number of surface defects exhibits capacitive-driven behavior at all scan rates,which may be attributed by N and P co-doping.Ex-situ transmission electron microscopy analyses in the fully discharged and charged states demonstrate structural sta-bility and reversibility owing to the expanded interlayer space.The suggested synthesis approach is simple and effective for producing heteroatom-doped carbon materials for PIBs and other advanced electrochemical energy stor-age materials.
查看更多>>摘要：With its unique 3D skeleton structure and exceptional cyclic stability,the Na+superionic conductor(NASICON)-type Na3V2(PO4)2F3(NVPF)has been con-sidered as a competitive cathode material for advanced Na-ion batteries.However,the release of fluorine during the heat treatment leads to the formation of an additional phase Na3V2(PO4)3(NVP),which results in a low-voltage plateau and compromises the energy density.Herein,we modulate the local electronic states of the V site by aluminum sub-stitution to strengthen the stability of F.The results confirm that the aluminum introduction not only changes the local electron states of V sites,significantly reducing the for-mation of NVP by-product from 6.71 wt％to 1.01 wt％,but also effectively reduces the band gap,improving the electronic conductivity of NVPF.The optimized Na3V1.9A10.1(PO4)2F3 exhibits higher energy density of 340 Wh-kg-1 and excellent rate performance of 106.7 mAh·g-1 at 10C compared with the pristine cathode.
查看更多>>摘要：Lithium-sulfur battery is one of the most promising battery systems for industrialization due to its high theoretical specific capacity and high energy density.Nonetheless,the"shuttle effect"has restrained the advancement of lithium-sulfur batteries.In this work,a gradient-structured nanofiber membrane with pure gelatin on one side and Super P-MoO2/MoS2-gelatin on the other side was created using a multi-step electrostatic spinning technique,which was applied for multi-functional separa-tor for lithium-sulfur batteries.The pure gelatin layer facing the anode side primarily homogenizes the lithium flux,whereas the Super P-MoO2/MoS2-gelatin layer facing the cathode side primarily adsorbs polysulfides by physical and chemical adsorption and enhancing polysulfide conversion efficiency.The findings demonstrate that even after 150 cycles at 0.2C,the lithium-sulfur battery can still sustain a discharge-specific capacity of 572.3 mAh-g-1.When used with Li||Li symmetric batteries,it has a cycle life of more than 1200 h.The commercialization of lithium-sulfur batteries is given a fresh idea by this straightforward preparation technique.
查看更多>>摘要：Hard carbon(HC)has emerged as one of the superior anode materials for sodium-ion batteries(SIBs),with its electrochemical performance significantly influ-enced by the presence of oxygen functional groups and its closed pore structure.However,current research on the structural adjustment of these oxygen functional groups and the closed pore architecture within HC remains lim-ited.Herein,energy-efficient and contamination-free spark plasma sintering technology was employed to tune the structure of coconut-shell HC,resulting in significant adjustments to the content of carboxyl(decreasing from 5.71 at％to 2.12 at％)and hydroxyl groups(decreasing from 7.73 at％to 6.26 at％).Crucially,these modifications reduced the irreversible reaction of oxygen functional groups with Na+.Simultaneously,a substantial number of closed pores with an average diameter of 1.22 nm were generated within the HC,offering an ideal environment for efficient Na+accommodation.These structural changes resulted in a remarkable improvement in the electro-chemical performance of the modified HC.The reversible specific capacity of the modified HC surged from 73.89 mAh-g-1 to an impressive 251.97 mAh-g-1 at a current density of 50 mA-g-1.Even at 400 mA-g-1,the reversible specific capacity increased significantly from 14.55 to 85.44 mAh-g-1.Hence,this study provides a novel perspective for designing tailored HC materials with the potential to develop high-performance SIBs.
Li SongXiao-Hong ZhongFang-Lin WangZhi-Hui Huang...
4286-4301页
查看更多>>摘要：The convenient synthesis of the composite electrode with high supercapacitance performance plays an important role in practical application but is challenging.Herein,the carbon nanotubes(CNTs)coupled with low-crystalline sulfur and nitrogen co-doped NiCo-LDH(de-noted as SN-NiCo-LDH)nanosheets array are grown on NiCo foam(NCF)substrate by two convenient steps of metal induced self-assembly and corrosion engineering,which present the advantages of operating at room-temperature and low preparation costs.Benefiting from the S-N co-doping and low-crystallinity of NiCo-LDH,the prepared SN-NiCo-LDH@CNTs@NCF electrode presents a topping charge capacity of 2470 C·g-1(4.94 C·cm-2)at 5 mA·cm-2.Furthermore,the fabricated asymmetry supercapacitor(ASC)achieves an extraordinary energy density of 77 Wh·kg-1(0.617 mWh·cm-2)at a power density of 438 W·kg-1(3.5 mW·cm-2)and outstanding stability(91％capacity retention after 5000 cycles at 20 mA·cm-2).Impressively,the structure evolution of NiCo-LDH during the charge/discharge processes has been thoroughly elucidated by in-situ Raman spectra.Therefore,this work verifies a powerful strategy and practical value for preparing composite electrodes with high supercapaci-tance performance,and also provides guidance for the rational design of the smart electrodes.
查看更多>>摘要：Surface engineering,which modulates the electronic structure and adsorption/desorption properties of electrocatalysts,is one of the key strategies for improving the catalytic performance.Herein,we demonstrate a facile solid-phase reaction for surface engineering of MnO2 to boost the oxygen reduction kinetics.Via reaction with surface hydroxy groups,La single atoms with loading amount up to 2.7 wt％are anchored onto α-MnO2 nanor-ods.After surface engineering,the oxygen reduction reaction(ORR)kinetics is significantly improved with the half-wave potential from 0.70 to 0.84 V,the number of transferred electrons from 2.5 to 3.9 and the limiting cur-rent density from 4.8 to 6.0 mA·cm-2.In addition,the catalyst delivers superior discharge performance in both alkaline and neutral metal-air batteries.Density functional theory(DFT)calculations reveal that atomic La modulates the surface electronic configuration of MnO2,reduces its d-band center and thus lowers the OOH*and O*reaction energy barrier.This work provides a new route for rational design of highly active electrocatalyst and holds great potential for application in various catalytic reactions.
查看更多>>摘要：Electrocatalysis provides an optimal approach for the conversion of carbon dioxide(CO2)into high-value chemicals,thereby presenting a promising avenue toward achieve carbon neutrality.However,addressing the selec-tivity and stability challenges of metal catalysts in elec-trolytic reduction remains a daunting task.In this study,the electrospinning method is employed to fabricate porous carbon nanofibers loaded with bismuth nanoparticles with the help of in situ pyrolysis.The porous carbon nanofibers as conductive support would facilitate the dispersion of bismuth active sites while inhibiting their aggregation and promoting the mass transfer,thus enhancing their electro-catalytic activity and stability.Additionally,nitrogen doping induces electron delocalization in bismuth atoms through metal-support interactions,thus enabling efficient adsorption of intermediates for improving selectivity based on the theoretical calculation.Consequently,Bi@PCNF-500 exhibits the exceptional selectivity and stability across a wide range of potential windows.Notably,its faradaic efficiency(FE)of formate reaches 92.7％in H-cell and 94.9％in flow cell,respectively,with good electrocatalytic stability.The in situ characterization and theoretical cal-culations elucidate the plausible reaction mechanism to obtain basic rules for designing efficient electrocatalyst.
查看更多>>摘要：Owing to the significant potential of alkaline seawater electrolysis for converting surplus power into eco-friendly hydrogen fuel,we developed bifunctional elec-trodes that integrate low-crystalline NiFe LDHs and amorphous NiFe alloy on a Ni foam(NF)substrate to enhance this process.Driven by the battery-like charac-teristics of NiFe LDHs,an anti-corrosive and active outer layer of NiFevacOOH continuously forms over time in the hybrid on the anode for the oxygen evolution reaction(OER),effectively mitigating powder shedding caused by corrosion induced by multiple anions in seawater.Mean-while,the strong bond between the hybrid and the NF substrate maintains intact hybrid coatings to ensure a rel-atively high overall conductivity of the electrodes,signif-icantly reducing the negative effects of structural degradation during the OER and hydrogen evolution reaction(HER),as well as the accumulation of contami-nants on the electrode surfaces.In long-term tests,these bifunctional hybrid electrodes maintained stable performance,even at a high current density of 500 mA·cm-2.The cell voltage increased by only 88 mV over 1000 h to 1.970 V during saline electrolysis and by 103 mV over 500 h to 2.062 V during seawater electroly-sis.Hence,this study provides valuable insights into effi-cient and stable seawater electrolysis using NiFe LDHs-NiFe alloy hybrids.
查看更多>>摘要：The utilization of piezo-photocatalytic technol-ogy for environmental remediation under full spectrum solar light is promising but still challenging.Herein,one-dimensional Bi2S3 nanowires,which can utilize both mechanical energy and near-infrared(NIR)light to remove hexavalent chromium(Cr(Ⅵ))efficiently,were synthe-sized by a restrained growth method.The reaction rate constants of Cr(Ⅵ)reduction in piezo-photocatalytic process under NIR(800-2500 nm)reached 0.334 min-1,which were 3.2 and 12.4 times as that of single piezo and photocatalytic process.The formation of polarized electric fields and one-dimensional structure allow ultrafast sepa-ration of charge carriers,thereby promoting the catalytic activity.Furthermore,due to the strong penetrability of NIR light,the piezo-photocatalysis performance in turbid solutions under NIR light(0.188 min-1)was even com-parable to that under visible light(0.186 min-1).This study provides a new concept on the development of piezo-photocatalytic technology for environmental remediation by utilization of NIR light and natural mechanical energy.
NETL
NSTL
万方数据