The uneven deposition and high reactivity of lithium-metal anode(LMA)lead to uncontrollable dendrite growth,low Coulombic efficiency,and safety concerns,hindering their commercialization.Here,a representative polar-ri...The uneven deposition and high reactivity of lithium-metal anode(LMA)lead to uncontrollable dendrite growth,low Coulombic efficiency,and safety concerns,hindering their commercialization.Here,a representative polar-rich-group triazine-based covalent organic framework(COF-TzDha)with a desolvation effect is designed as an interlayer for stable,dendrite-free LMA.The abundant triazine rings in COFTzDha as a donor effectively attract lithium ions,while the one-dimensional nanopore structure facilitates lithium-ion migration.The periodic arrangement of polar groups(-OH)in the backbone interacts with electrolyte components(DOL,DME,TFSI-)to form a hydrogen bonding network that slows solvent molecules transport.Therefore,COF-TzDha effectively desolvates lithium ions from the solvent sheath,promoting uniform lithium ion flux and Li plating/stripping.Theoretical calculations verify that COFTzDha with abundant adsorption sites and strong adsorption energy facilitates lithium ion desolvation.Consequently,the introduction of COF-TzDha obtains a high ion mobility(0.75).The Li|COF@PP|Li symmetric cell cycles stably for over 1200 h at 4 mA cm^(-2)/4.0 mA h cm^(-2).The Li|COF@PP|LiFePO_(4)full cell also displays highly stable cycling performance with 600 cycles(75.5%capacity retention,~100% Coulombic efficiency)at 1 C.This work verifies an effective strategy for inducing uniform Li deposition and achieving dendrite-free,stable LMA using a polar-rich-group COF interlayer with a desolvation effect.展开更多
Lithium-sulfur(Li-S) batteries have generated significant attention due to their high theoretical specific capacity and energy density among a host of energy storage power devices.Nevertheless,the lithium polysulfide ...Lithium-sulfur(Li-S) batteries have generated significant attention due to their high theoretical specific capacity and energy density among a host of energy storage power devices.Nevertheless,the lithium polysulfide dissolution shuttle that occurs within Li-S batteries will lead to capacity deterioration and inadequate cycling stability.In the paper,we proposed a measure to deal with the above problems by modifying the separator with Nd_(2)O_(3)/graphene composite in Li-S batteries.Graphene's special chemical properties and structural qualities make it an excellent choice for Li-S batteries.Meanwhile,Nd_(2)O_(3) has a strong binding affinity with lithium polysulfide due to its low electronegativity,which exhibits Lewis' s acidity and forms strong interactions with lithium polysulfide,which is strongly Lewis basic.By utilizing these advantageous properties,Li-S batteries assembling Nd_(2)O_(3)-decorated reduced graphite oxide modified polypropylene separators(Nd_(2)O_(3)/RGO/PP) demonstrate outstanding electrochemical performance,including a mere 0.0525% capacity attenuation rate under 2C during 1000 cycles and with exceptional rate performance of 614 mAh/g even at 3C.This study presents valuable knowledge for effectively modifying separators using rare earth oxides to incorporate graphene,ultimately promoting the practical application of Li-S batteries.展开更多
Nickel-rich layered oxide cathode(LiNi_(x)Co_(y)Mn_(1−x−y)O_(2),x>0.5,NCM)shows substantial potential for applications in longer-range electrical vehicles.However,the rapid capacity decay and serious safety concern...Nickel-rich layered oxide cathode(LiNi_(x)Co_(y)Mn_(1−x−y)O_(2),x>0.5,NCM)shows substantial potential for applications in longer-range electrical vehicles.However,the rapid capacity decay and serious safety concerns impede its practical viability.This work provides a hydrogen-bonded organic framework(HOF)modification strategy to simultaneously improve the electrochemical performance,thermal stability and incombustibility of separator.Melamine cyanurate(MCA),as a low-cost and reliable flame-retardant HOF,was implemented in the separator modification layer,which can prevent the battery short circuit even at a high temperature.In addition,the supermolecule properties of MCA provide unique physical and chemical microenvironment for regulating ion-transport behavior in electrolyte.The MCA coating layer enabled the nickel-rich layered oxide cathode with a high-capacity retention of 90.3%after 300 cycles at 1.0 C.Collectively,the usage of MCA in lithium-ion batteries(LIBs)affords a simple,low-cost and efficient strategy to improve the security and service life of nickel-rich layered cathodes.展开更多
In lithium-sulfur batteries(LSBs),the limited utilization of sulfur and the sluggish kinetics of redox reaction significantly hinder their electrochemical performance,especially under high rates and high sulfur loadin...In lithium-sulfur batteries(LSBs),the limited utilization of sulfur and the sluggish kinetics of redox reaction significantly hinder their electrochemical performance,especially under high rates and high sulfur loadings.Here,we propose a novel separator structure with an interlayer composed of a vermiculite nanosheet combined with Ketjen Black(VMT@KB)for LSBs,facilitating efficient adsorption and rapid catalytic conversion toward lithium polysulfides(LiPSs).The VMT@KB nanosheets with an electrical double-layer structure and electronic conductivity are obtained through a high-temperature peeling process and Li^(+)exchange treatment in LiCl solution,followed by a mechanical combination process with KB.The results demonstrate that incorporating VMT@KB as an interlayer on a conventional separator enhances the conductivity and limits the LiPSs in the cathode region.The Li-S cell with VMT@KB interlayer shows satisfactory cycle and rate performance,especially in high sulfur loading.It exhibits a remarkable initial discharge capacity of 1225 mAh g^(-1)at 0.5 C and maintains a capacity of 816 mAh g^(-1)after 500 cycles.Besides,the discharge capacity remains 462 mAh g^(-1)even at 6 C.Moreover,the cell with high sulfur loading(8.2 mg cm^(-2))enables stable cycling for 100 cycles at 0.1 C with a discharge capacity of over1000 mAh g^(-1).展开更多
The efficient limitation of the"shuttle effect"of polysulfide from the rational construction of electrocatalysts to accelerate the redox kinetics of polysulfides is extremely important.In this work,the cobal...The efficient limitation of the"shuttle effect"of polysulfide from the rational construction of electrocatalysts to accelerate the redox kinetics of polysulfides is extremely important.In this work,the cobalt/Nickel bimetallic alloy polyhedrons decorated on layered TiO_(2)heterostructure(Co Ni@TiO_(2)/C)derived from MXene and bimetallic metal-organic framework have been prepared through liquid-phase deposition and high-temperature annealing processes.This heterostructure presents excellent electrical conductivity,which facilitates ion diffusion and electron transfer within the battery.Besides,the heterostructure from anchoring the Co Ni bimetallic alloy on the layered TiO_(2)ensures the full exposure of active sites and accelerates polysulfide redox kinetics through chemisorption and catalytic conversion.Considering these advantages mentioned above,when applied as the lithium-sulfur batteries(LSBs)separator modifier,the cell assembled from the Co Ni@TiO_(2)/C modified separator demonstrates high specific capacity(1481.7 mAh/g at 0.5 C),superior rate capability(855.5 mAh/g at 3 C)and excellent cycling performance,which can maintain the high capacity of 856.09 mAh/g after 300 cycles with low capacity decay rate of 0.09%per cycle.Even under a high sulfur loading of 4.4 mg/cm^(2),the cell can still present excellent cycling stability.This study paves the way for the design of novel material for the construction of an outstanding functional separator layer and shines the light on the effective and feasible way for the inhibition of shuttle effect in lithium-sulfur batteries.展开更多
A new Fe3C-N-doped reduced graphene oxide(Fe3C-N-rGO)prepared by a facile method is used as a separator for high performance lithium-sulfur(Li-S)batteries.The Fe3C-N-rGO is coated on the surface of commercial polyprop...A new Fe3C-N-doped reduced graphene oxide(Fe3C-N-rGO)prepared by a facile method is used as a separator for high performance lithium-sulfur(Li-S)batteries.The Fe3C-N-rGO is coated on the surface of commercial polypropylene separator(Celgard 2400)close to the sulfur cathode.The special nanotubes are in-situ catalyzed by Fe3C nanoparticles.They could entrap lithium polysulfides(Li PSs)to restrain the shuttle effect and reduce the loss of active material.The battery with the modified separator and sulfur cathode shows an excellent cycle performance.It has a high rate performance,580.5 mAh/g at the high current rate of 4 C relative to 1075 mAh/g at 0.1 C.It also has an initial discharge capacity of 774.8 m Ah/g measured at 0.5 C and remains 721.8 mAh/g after 100 cycles with a high capacity retention of 93.2%.The outstanding performances are notable in recently reports with modified separator.展开更多
By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ODE method is developed for solving the mKdV-sinh-Gordon equation. As a result, many explicit and exact sol...By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ODE method is developed for solving the mKdV-sinh-Gordon equation. As a result, many explicit and exact solutions including some new formal solutions are successfully picked up for the mKdV-sinh-Gordon equation by this approach.展开更多
By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ordinary differential equation method is presented for solving the （2 ＋ 1）-dimensional sine-Poisson equa...By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ordinary differential equation method is presented for solving the （2 ＋ 1）-dimensional sine-Poisson equation. As a result, many explicit and exact solutions of the （2 ＋ 1）-dimensional sine-Poisson equation are derived in a simple manner by this technique.展开更多
Two types of modified silica gels were prepared by adsorption method and bonding method respectively. Enrichment and separation of trace metal ions have been done by using the column packed with modified silica gels.
The practical applications of lithium-sulfur(Li-S)batteries are hampered by the sluggish redox kinetics and polysulfides shuttle in the cyclic process,which leads to a series of problems including the loss of active m...The practical applications of lithium-sulfur(Li-S)batteries are hampered by the sluggish redox kinetics and polysulfides shuttle in the cyclic process,which leads to a series of problems including the loss of active materials and poor cycling efficiency.In this paper,the pore structures of carbon nanosheets based electrocatalysts were precisely controlled by regulating the content of water-soluble KCl template.The relationship between pore structures and Li-S electrochemical behavior was studied,which demonstrates a key influence of pore structure in polysulfides phase conversions.In the liquid-sloid redox reaction of polysulfides,the micropores and small mesopores(d<20 nm)exhibited little impact,while the meso-pores(d>20 nm)and macropores played a decisive role.As a typical exhibition,the nickel-embedded carbon nanosheets(Ni-CNS)with a high content of large mesopores and macropores can aid Li-S batteries in exhibiting stable cycling performance(760.1 mAh g^(-1)at 1 C after 300 cycles)and superior rate capac-ity(847.8 mAh g^(-1)at 2 C).Furthermore,even with high sulfur loading(8 mg cm^(−2))and low electrolyte(E/S is around 6μL mg^(-1)),the high area capacity of 7.7 mAh cm^(−2)at 0.05 C could be achieved.This work can provide a guideline for the design of the pore structure of carbon-based electrocatalysts toward high-efficiency sulfur species redox reactions,and afford a general,controllable,and simple approach to constructing high performance Li-S batteries.展开更多
Lithium sulfur(Li-S)battery is a kind of burgeoning energy storage system with high energy density.However,the electrolyte-soluble intermediate lithium polysulfides(Li PSs)undergo notorious shuttle effect,which seriou...Lithium sulfur(Li-S)battery is a kind of burgeoning energy storage system with high energy density.However,the electrolyte-soluble intermediate lithium polysulfides(Li PSs)undergo notorious shuttle effect,which seriously hinders the commercialization of Li-S batteries.Herein,a unique VSe_(2)/V_(2)C heterostructure with local built-in electric field was rationally engineered from V_(2)C parent via a facile thermal selenization process.It exquisitely synergizes the strong affinity of V_(2)C with the effective electrocatalytic activity of VSe_(2).More importantly,the local built-in electric field at the heterointerface can sufficiently promote the electron/ion transport ability and eventually boost the conversion kinetics of sulfur species.The Li-S battery equipped with VSe_(2)/V_(2)C-CNTs-PP separator achieved an outstanding initial specific capacity of 1439.1 m A h g^(-1)with a high capacity retention of 73%after 100 cycles at0.1 C.More impressively,a wonderful capacity of 571.6 mA h g^(-1)was effectively maintained after 600cycles at 2 C with a capacity decay rate of 0.07%.Even under a sulfur loading of 4.8 mg cm^(-2),areal capacity still can be up to 5.6 m A h cm^(-2).In-situ Raman tests explicitly illustrate the effectiveness of VSe_(2)/V_(2)C-CNTs modifier in restricting Li PSs shuttle.Combined with density functional theory calculations,the underlying mechanism of VSe_(2)/V_(2)C heterostructure for remedying Li PSs shuttling and conversion kinetics was deciphered.The strategy of constructing VSe_(2)/V_(2)C heterocatalyst in this work proposes a universal protocol to design metal selenide-based separator modifier for Li-S battery.Besides,it opens an efficient avenue for the separator engineering of Li-S batteries.展开更多
The transformation of Li_(2)S_(2)-Li_(2)S is indubitably the most crucial and labored rate-limiting step among the sophisticated reactions for the lithium-sulfur batteries(LSBs),the adjustment of which is anticipated ...The transformation of Li_(2)S_(2)-Li_(2)S is indubitably the most crucial and labored rate-limiting step among the sophisticated reactions for the lithium-sulfur batteries(LSBs),the adjustment of which is anticipated to impede the shuttle effect.Herein,a N,Se dual-doped carbon nanocages embedded by Co-CoSe_(2)nanoparticles(Co-CoSe_(2)@NSeC)is employed as a functional coating layer on commercial separator to improve the performance of LSBs.The well-designed N,Se co-doped nanostructures endow the modified layer with a satisfactory capacity for blocking polysulfides.Both calculations and experiments jointly disclose that the Li_(2)S_(2)to Li_(2)S reaction,including the liquid-solid conversion,was prominently expedited both thermodynamically and electrodynamically.Consequently,the batteries fabricated with Co-CoSe_(2)@NSeC modified separator can deliver a favorable 764.2 mAh g^(−1)with 8.0 C,accompanied by a salient long cycling lifespan(only 0.066%at 1 C and 0.061%under 2 C after 1000 and 2000 cycles),and a desired anode protection.In addition,despite a raised areal loading of 7.53 mg cm^(−2)was introduced,the cells assembled by Co-CoSe_(2)@NSeC@PP are allowed to produce an outstanding initial behavior of 8.71 mAh cm^(−2)under 0.2 C.This work may reinforce further explorations and serve with valuable insights into N,Se dual-doping materials for high-performance LSBs.展开更多
The distribution rules of impurities in distilled terbium metal were investigated by vacuum distillation purificationexperiment and theoretical analysis.It is found that Ti impurity in distilled terbium is220mg/kg in ...The distribution rules of impurities in distilled terbium metal were investigated by vacuum distillation purificationexperiment and theoretical analysis.It is found that Ti impurity in distilled terbium is220mg/kg in the initial stage of the distillationpurification,increases slowly in the middle stage,and increases rapidly in the last stage,reaching2260mg/kg,and the modifiedseparation coefficient of Ti is1/19.02.The diffusion of the impurity Ti in liquid metal can reach a quasi-equilibrium state in theinitial stage of distillation purification and the calculated results agree well with experimental results;the distribution profile ofimpurity Cu is opposite to Ti,being380mg/kg in the initial stage,decreasing linearly to290mg/kg in the last stage,and themodified separation coefficient is17.99,and the theoretical calculated results are inconsistent with the experimental result.展开更多
The distribution rules of impurities contents in distilled metallic dysprosium were researched, and a theoretical analysis was carried out. The research results indicated that, the content of impurity in distilled met...The distribution rules of impurities contents in distilled metallic dysprosium were researched, and a theoretical analysis was carried out. The research results indicated that, the content of impurity in distilled metal, such as Al and Fe, was lower in the ini-tial stage, increased slowly in the middle stage, and increased rapidly in the last stage during the process of distillation purification. The calculated method of separation coefficient of impurity in crude metal by content of impurity in distilled metal was not suitable for high pure metals, and the modified separation coefficient was proposed, and it equaled 1/6.1 and 1/16.9 for impurity Al and Fe. The physical process of distillation was coincident with that of solidification essentially, and solute re-distribution theory in solidify-ing front could be used to describe the impurity distribution near evaporating surface. In the former stage of distillation purification, the diffusion of impurity in liquid metal could reach a quasi-equilibrium state, the calculated result of impurity content in distilled metal agreed well with experiments. In the latter stage of distillation process, the diffusion rate of impurity in liquid metal decreased, and the content in distilled metal was larger than the calculated result.展开更多
The lithium polysulfide shuttle and sluggish sulfur reaction kinetics still pose significant challenges to lithium-sulfur(Li-S)batteries.The functional plane of Fe-MoSe_(2)@r GO nanohybrid with abundant defects has be...The lithium polysulfide shuttle and sluggish sulfur reaction kinetics still pose significant challenges to lithium-sulfur(Li-S)batteries.The functional plane of Fe-MoSe_(2)@r GO nanohybrid with abundant defects has been designed and applied in Li-S batteries to develop the functional separator and multi-layer sulfur cathode.The cell with a functional separator exhibits a retention capacity of 462 m Ah g^(-1)after the 1000th at 0.5 C and 516 m Ah g^(-1)after the 600th at 0.3 C.Even at low electrolyte conditions(7.0μL_(mgsulfur)^(-1)and 15μL_(mgsulfur)^(-1))under high sulfur loadings(3.46 mg cm^(-2)and 3.73 mg cm^(-2)),the cell still presents high reversible discharge capacities 679 and 762 m Ah g^(-1)after 70 cycles,respectively.Further,at sulfur loadings up to 8.26 and 5.2 mg cm^(-2),the cells assembled with the bi-layers sulfur cathode and the tri-layers sulfur cathode give reversible capacities of 3.3 m Ah cm^(-2)after the 100th cycle and 3.0 m Ah cm^(-2)after the 120th cycle,respectively.This research not only demonstrates that the FeMoSe_(2)@r GO functional plane is successfully designed and applied in Li-S batteries with superior electrochemical performances but also paves the novel way for developing a unique multi-layer cathode technique to enhance and advance the electrochemical behavior of Li-S cells at a high-sulfur-loading cathode under lean electrolyte/sulfur(E/S)ratio.展开更多
In 2011,a new class of 2D materials was discovered;after 2012,they began to be concerned;in 2017,the“gold rush”of the materials was triggered,and they are exactly MXenes.2D MXenes,a new class of transition metal car...In 2011,a new class of 2D materials was discovered;after 2012,they began to be concerned;in 2017,the“gold rush”of the materials was triggered,and they are exactly MXenes.2D MXenes,a new class of transition metal carbides,carbonitrides and nitrides,have become the star and cutting-edge research materials in the field of emerging batteries systems due to their unique 2D structure,abundant surface chemistry,and excellent physical and electrochemical properties.This review focuses on the MXene materials and summarizes the recent advancements in the synthesis techniques and properties,in addition to a detailed discussion on the electrochemical energy storage applications,including alkali-ion(Li^(+),Na^(+),K^(+))storage,lithium-sulfur(Li–S)batteries,sodiumsulfur(Na–S)batteries,and metal anode protection.Special attentions are given to the elaborate design of nano-micro structures of MXenes for the various roles as electrodes,multifunctional components,S hosts,modified separators,and metal anode protective layers.The paper ends with a prospective summary of the promising research directions in terms of synthesis,structure,properties,analysis,and production on MXene materials.展开更多
In this paper, the Schr?dinger equation is solved by Modified separation of variables (MSV) method suggested by Pishkoo and Darus. Using this method, Meijer’s G-function solutions are derived in cylindrical coordinat...In this paper, the Schr?dinger equation is solved by Modified separation of variables (MSV) method suggested by Pishkoo and Darus. Using this method, Meijer’s G-function solutions are derived in cylindrical coordinate system for quantum particle in cylindrical can. All elementary functions and most of the special functions which are the solution of extensive problems in physics and engineering are special cases of Meijer’s G-functions.展开更多
The polysulfide shuttling and sluggish redox kinetics,due to the notorious adsorption-catalysis underperformance,are the ultimate obstacles of the practical application of lithium-sulfur(Li-S)batteries.Conventional ca...The polysulfide shuttling and sluggish redox kinetics,due to the notorious adsorption-catalysis underperformance,are the ultimate obstacles of the practical application of lithium-sulfur(Li-S)batteries.Conventional carbon-based and transition metal compound-based material solutions generally suffer from poor catalysis and adsorption,respectively,despite the performance gain in terms of the other.Herein,we have enhanced polysulfide adsorptioncatalytic capability and protected the Li anode using a complementary bimetallic carbide electrocatalyst,Co3 Mo3 C,modified commercial separator.With this demonstration,the potentials of bimetal compounds,which have been well recognized in other environmental catalysis,are also extended to Li-S batteries.Coupled with this modified separator,a simple cathode(S/Super P composite)can deliver high sulfur utilization,high rate performance,and excellent cycle stability with a low capacity decay rate of^0.034%per cycle at 1 C up to1000 cycles.Even at a high S-loading of 8.0 mg cm^-2 with electrolyte/sulfur ratio=6 m L g^-1,the cathode still exhibits high areal capacity of^6.8 m A h cm^-2.The experimental analysis and the first-principles calculations proved that the bimetallic carbide Co3 Mo3 C provides more binding sites for adsorbing polysulfides and catalyzing the multiphase conversion of sulfur/polysulfide/sulfide than monometallic carbide Mo2 C.Moreover,the modified separator can be reutilized with comparable electrochemical performance.We also showed other bimetallic carbides with similar catalytic effects on Li-S batteries and this material family has great promise indifferent energy electrocatalytic systems.展开更多
The intrinsic sluggish conversion kinetics and severe shuttle effect in lithium-sulfur(Li-S)batteries are responsible for their poor reversible capacity and cycling longevity,which have greatly hindered their practica...The intrinsic sluggish conversion kinetics and severe shuttle effect in lithium-sulfur(Li-S)batteries are responsible for their poor reversible capacity and cycling longevity,which have greatly hindered their practical applications.To address these drawbacks,herein,we design and construct a heterostructured Ni/Ni_(2)P embedded in a mesoporous carbon nanosphere composite(Ni/Ni_(2)P-MCN)for boosting polysulfide catalytic conversion in Li-S batteries.The Ni/Ni_(2)PMCN-modified separator could not only prevent the shuttle effect significantly through abundant chemical adsorptive sites,but also demonstrate superior catalytic reactivities for the conversion of polysulfides.More importantly,the conductive carbon matrix with an exposed mesoporous structure can serve as an effective physical barrier to accommodate deposited insoluble Li_(2)S.Consequently,the cells with the Ni/Ni_(2)P-MCN-modified separator exhibit greatly boosted rate capability(431 mA h g^(-1) at 5 C)and cycling stability(a capacity decay of 0.031% per cycle after 1500 cycles).Even at an enhanced sulfur loading of 4.2 mg cm^(-2),a stable and superior areal capacity(about 3.5 mA h cm^(-2))has been demonstrated.We envision that the unique Ni/Ni_(2)P heterostructure in the porous carbon matrix could offer great potential for highperformance and sustained energy storage devices.展开更多
Lithium-sulfur(Li-S)batteries are highly regarded as the next-generation high-energy-density secondary batteries due to their high capacity and large theoretical energy density.However,the practical application of the...Lithium-sulfur(Li-S)batteries are highly regarded as the next-generation high-energy-density secondary batteries due to their high capacity and large theoretical energy density.However,the practical application of these batteries is hindered mainly by the polysulfide shuttle issue.Herein,we designed and synthesized a new lithium sulfonylimide covalent organic framework(COF)material(COF-LiSTFSI,LiSTFSI=lithium(4-styrenesulfonyl)(trifluoromethanesulfonyl)imide),and further used it to modify the common polypropylene(PP)separator of Li-S batteries.The COF-LiSTFSI with sulfonylimide anion groups features stronger electronegativity,thus can effectively facilitate the lithium ion conduction while significantly suppress the diffusion of polysulfides via the electrostatic interaction.Compared with the unmodified PP separator,the COF-LiSTFSI modified separator results in a high ionic conductivity(1.50 mS·cm^(−1))and Li+transference number(0.68).Consequently,the Li-S battery using the COF-LiSTFSI modified separator achieves a high capacity of 1229.7 mAh·g^(−1)at 0.2 C and a low decay rate of only 0.042%per cycle after 1000 cycles at 1 C,compared with those of 941.5 mAh·g^(−1)and 0.061%using the unmodified PP separator,respectively.These results indicate that by choosing suitable functional groups,an effective strategy for COF-modified separators could be developed for high-performance Li-S batteries.展开更多
基金supported by the National Natural Science Foundation of China(No.51972066)the Natural Science Foundation of Guangdong Province of China(No.2024A1515012499)。
文摘The uneven deposition and high reactivity of lithium-metal anode(LMA)lead to uncontrollable dendrite growth,low Coulombic efficiency,and safety concerns,hindering their commercialization.Here,a representative polar-rich-group triazine-based covalent organic framework(COF-TzDha)with a desolvation effect is designed as an interlayer for stable,dendrite-free LMA.The abundant triazine rings in COFTzDha as a donor effectively attract lithium ions,while the one-dimensional nanopore structure facilitates lithium-ion migration.The periodic arrangement of polar groups(-OH)in the backbone interacts with electrolyte components(DOL,DME,TFSI-)to form a hydrogen bonding network that slows solvent molecules transport.Therefore,COF-TzDha effectively desolvates lithium ions from the solvent sheath,promoting uniform lithium ion flux and Li plating/stripping.Theoretical calculations verify that COFTzDha with abundant adsorption sites and strong adsorption energy facilitates lithium ion desolvation.Consequently,the introduction of COF-TzDha obtains a high ion mobility(0.75).The Li|COF@PP|Li symmetric cell cycles stably for over 1200 h at 4 mA cm^(-2)/4.0 mA h cm^(-2).The Li|COF@PP|LiFePO_(4)full cell also displays highly stable cycling performance with 600 cycles(75.5%capacity retention,~100% Coulombic efficiency)at 1 C.This work verifies an effective strategy for inducing uniform Li deposition and achieving dendrite-free,stable LMA using a polar-rich-group COF interlayer with a desolvation effect.
基金Project supported by Guangzhou Science and Technology Project,China (201803020038)Guangdong Science and Technology Commissioner Project (GDKTP2020046700)Innovation and Entrepreneurship Training Program for University Students (202324040)。
文摘Lithium-sulfur(Li-S) batteries have generated significant attention due to their high theoretical specific capacity and energy density among a host of energy storage power devices.Nevertheless,the lithium polysulfide dissolution shuttle that occurs within Li-S batteries will lead to capacity deterioration and inadequate cycling stability.In the paper,we proposed a measure to deal with the above problems by modifying the separator with Nd_(2)O_(3)/graphene composite in Li-S batteries.Graphene's special chemical properties and structural qualities make it an excellent choice for Li-S batteries.Meanwhile,Nd_(2)O_(3) has a strong binding affinity with lithium polysulfide due to its low electronegativity,which exhibits Lewis' s acidity and forms strong interactions with lithium polysulfide,which is strongly Lewis basic.By utilizing these advantageous properties,Li-S batteries assembling Nd_(2)O_(3)-decorated reduced graphite oxide modified polypropylene separators(Nd_(2)O_(3)/RGO/PP) demonstrate outstanding electrochemical performance,including a mere 0.0525% capacity attenuation rate under 2C during 1000 cycles and with exceptional rate performance of 614 mAh/g even at 3C.This study presents valuable knowledge for effectively modifying separators using rare earth oxides to incorporate graphene,ultimately promoting the practical application of Li-S batteries.
基金supported by the National Key Research and Development Program of China(No.2022YFA1504100)the National Natural Science Foundation of China(Nos.22005215,22279089,and 22178251).
文摘Nickel-rich layered oxide cathode(LiNi_(x)Co_(y)Mn_(1−x−y)O_(2),x>0.5,NCM)shows substantial potential for applications in longer-range electrical vehicles.However,the rapid capacity decay and serious safety concerns impede its practical viability.This work provides a hydrogen-bonded organic framework(HOF)modification strategy to simultaneously improve the electrochemical performance,thermal stability and incombustibility of separator.Melamine cyanurate(MCA),as a low-cost and reliable flame-retardant HOF,was implemented in the separator modification layer,which can prevent the battery short circuit even at a high temperature.In addition,the supermolecule properties of MCA provide unique physical and chemical microenvironment for regulating ion-transport behavior in electrolyte.The MCA coating layer enabled the nickel-rich layered oxide cathode with a high-capacity retention of 90.3%after 300 cycles at 1.0 C.Collectively,the usage of MCA in lithium-ion batteries(LIBs)affords a simple,low-cost and efficient strategy to improve the security and service life of nickel-rich layered cathodes.
基金financially supported by the National Natural Science Foundation of China(52172245)the Key Scientific and Technological Innovation Project of Shandong(2023CXGC010302)the Qingdao Flexible Materials Precision Die-cutting Technology Innovation Center。
文摘In lithium-sulfur batteries(LSBs),the limited utilization of sulfur and the sluggish kinetics of redox reaction significantly hinder their electrochemical performance,especially under high rates and high sulfur loadings.Here,we propose a novel separator structure with an interlayer composed of a vermiculite nanosheet combined with Ketjen Black(VMT@KB)for LSBs,facilitating efficient adsorption and rapid catalytic conversion toward lithium polysulfides(LiPSs).The VMT@KB nanosheets with an electrical double-layer structure and electronic conductivity are obtained through a high-temperature peeling process and Li^(+)exchange treatment in LiCl solution,followed by a mechanical combination process with KB.The results demonstrate that incorporating VMT@KB as an interlayer on a conventional separator enhances the conductivity and limits the LiPSs in the cathode region.The Li-S cell with VMT@KB interlayer shows satisfactory cycle and rate performance,especially in high sulfur loading.It exhibits a remarkable initial discharge capacity of 1225 mAh g^(-1)at 0.5 C and maintains a capacity of 816 mAh g^(-1)after 500 cycles.Besides,the discharge capacity remains 462 mAh g^(-1)even at 6 C.Moreover,the cell with high sulfur loading(8.2 mg cm^(-2))enables stable cycling for 100 cycles at 0.1 C with a discharge capacity of over1000 mAh g^(-1).
基金supported by National Natural Science Foundation of China(Nos.52472194,52101243)Natural Science Foundation of Guangdong Province,China(No.2023A1515012619)the Science and Technology Planning Project of Guangzhou(No.202201010565)。
文摘The efficient limitation of the"shuttle effect"of polysulfide from the rational construction of electrocatalysts to accelerate the redox kinetics of polysulfides is extremely important.In this work,the cobalt/Nickel bimetallic alloy polyhedrons decorated on layered TiO_(2)heterostructure(Co Ni@TiO_(2)/C)derived from MXene and bimetallic metal-organic framework have been prepared through liquid-phase deposition and high-temperature annealing processes.This heterostructure presents excellent electrical conductivity,which facilitates ion diffusion and electron transfer within the battery.Besides,the heterostructure from anchoring the Co Ni bimetallic alloy on the layered TiO_(2)ensures the full exposure of active sites and accelerates polysulfide redox kinetics through chemisorption and catalytic conversion.Considering these advantages mentioned above,when applied as the lithium-sulfur batteries(LSBs)separator modifier,the cell assembled from the Co Ni@TiO_(2)/C modified separator demonstrates high specific capacity(1481.7 mAh/g at 0.5 C),superior rate capability(855.5 mAh/g at 3 C)and excellent cycling performance,which can maintain the high capacity of 856.09 mAh/g after 300 cycles with low capacity decay rate of 0.09%per cycle.Even under a high sulfur loading of 4.4 mg/cm^(2),the cell can still present excellent cycling stability.This study paves the way for the design of novel material for the construction of an outstanding functional separator layer and shines the light on the effective and feasible way for the inhibition of shuttle effect in lithium-sulfur batteries.
基金supported by the National Natural Science Foundation of China(Grant no.51672075,21271069,51772092,51704106)Science and Technology Program of Hunan Province(Grant no.2015JC3049)
文摘A new Fe3C-N-doped reduced graphene oxide(Fe3C-N-rGO)prepared by a facile method is used as a separator for high performance lithium-sulfur(Li-S)batteries.The Fe3C-N-rGO is coated on the surface of commercial polypropylene separator(Celgard 2400)close to the sulfur cathode.The special nanotubes are in-situ catalyzed by Fe3C nanoparticles.They could entrap lithium polysulfides(Li PSs)to restrain the shuttle effect and reduce the loss of active material.The battery with the modified separator and sulfur cathode shows an excellent cycle performance.It has a high rate performance,580.5 mAh/g at the high current rate of 4 C relative to 1075 mAh/g at 0.1 C.It also has an initial discharge capacity of 774.8 m Ah/g measured at 0.5 C and remains 721.8 mAh/g after 100 cycles with a high capacity retention of 93.2%.The outstanding performances are notable in recently reports with modified separator.
基金Project supported by the National Natural Science Foundation of China (Grant No 10672053)
文摘By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ODE method is developed for solving the mKdV-sinh-Gordon equation. As a result, many explicit and exact solutions including some new formal solutions are successfully picked up for the mKdV-sinh-Gordon equation by this approach.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10672053)
文摘By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ordinary differential equation method is presented for solving the （2 ＋ 1）-dimensional sine-Poisson equation. As a result, many explicit and exact solutions of the （2 ＋ 1）-dimensional sine-Poisson equation are derived in a simple manner by this technique.
文摘Two types of modified silica gels were prepared by adsorption method and bonding method respectively. Enrichment and separation of trace metal ions have been done by using the column packed with modified silica gels.
基金supported by the National Natu-ral Science Foundation of China(Nos.U2004172,51972287)the National Natural Science Foundation of Henan Province(Nos.202300410368,222301420039)+2 种基金the Foundation for University Key Teacher of Henan Province(No.2020GGJS009)the Science&Technology Innovation Talents in Universities of Henan Province(No.23HASTIT001)the China Postdoctoral Science Foundation(No.2021M692898).
文摘The practical applications of lithium-sulfur(Li-S)batteries are hampered by the sluggish redox kinetics and polysulfides shuttle in the cyclic process,which leads to a series of problems including the loss of active materials and poor cycling efficiency.In this paper,the pore structures of carbon nanosheets based electrocatalysts were precisely controlled by regulating the content of water-soluble KCl template.The relationship between pore structures and Li-S electrochemical behavior was studied,which demonstrates a key influence of pore structure in polysulfides phase conversions.In the liquid-sloid redox reaction of polysulfides,the micropores and small mesopores(d<20 nm)exhibited little impact,while the meso-pores(d>20 nm)and macropores played a decisive role.As a typical exhibition,the nickel-embedded carbon nanosheets(Ni-CNS)with a high content of large mesopores and macropores can aid Li-S batteries in exhibiting stable cycling performance(760.1 mAh g^(-1)at 1 C after 300 cycles)and superior rate capac-ity(847.8 mAh g^(-1)at 2 C).Furthermore,even with high sulfur loading(8 mg cm^(−2))and low electrolyte(E/S is around 6μL mg^(-1)),the high area capacity of 7.7 mAh cm^(−2)at 0.05 C could be achieved.This work can provide a guideline for the design of the pore structure of carbon-based electrocatalysts toward high-efficiency sulfur species redox reactions,and afford a general,controllable,and simple approach to constructing high performance Li-S batteries.
基金supported by the National Natural Science Foundation of China(No.52072099)the Joint Guidance Project of the Natural Science Foundation of Heilongjiang Province,China(No.LH2022E093)the Team Program of the Natural Science Foundation of Heilongjiang Province,China(No.TD2021E005)。
文摘Lithium sulfur(Li-S)battery is a kind of burgeoning energy storage system with high energy density.However,the electrolyte-soluble intermediate lithium polysulfides(Li PSs)undergo notorious shuttle effect,which seriously hinders the commercialization of Li-S batteries.Herein,a unique VSe_(2)/V_(2)C heterostructure with local built-in electric field was rationally engineered from V_(2)C parent via a facile thermal selenization process.It exquisitely synergizes the strong affinity of V_(2)C with the effective electrocatalytic activity of VSe_(2).More importantly,the local built-in electric field at the heterointerface can sufficiently promote the electron/ion transport ability and eventually boost the conversion kinetics of sulfur species.The Li-S battery equipped with VSe_(2)/V_(2)C-CNTs-PP separator achieved an outstanding initial specific capacity of 1439.1 m A h g^(-1)with a high capacity retention of 73%after 100 cycles at0.1 C.More impressively,a wonderful capacity of 571.6 mA h g^(-1)was effectively maintained after 600cycles at 2 C with a capacity decay rate of 0.07%.Even under a sulfur loading of 4.8 mg cm^(-2),areal capacity still can be up to 5.6 m A h cm^(-2).In-situ Raman tests explicitly illustrate the effectiveness of VSe_(2)/V_(2)C-CNTs modifier in restricting Li PSs shuttle.Combined with density functional theory calculations,the underlying mechanism of VSe_(2)/V_(2)C heterostructure for remedying Li PSs shuttling and conversion kinetics was deciphered.The strategy of constructing VSe_(2)/V_(2)C heterocatalyst in this work proposes a universal protocol to design metal selenide-based separator modifier for Li-S battery.Besides,it opens an efficient avenue for the separator engineering of Li-S batteries.
基金supported by the National Natural Science Foundation of China(No.21875039)the Project on the Integration of Industry-Education-Research of Fujian Province(No.2021H6020).
文摘The transformation of Li_(2)S_(2)-Li_(2)S is indubitably the most crucial and labored rate-limiting step among the sophisticated reactions for the lithium-sulfur batteries(LSBs),the adjustment of which is anticipated to impede the shuttle effect.Herein,a N,Se dual-doped carbon nanocages embedded by Co-CoSe_(2)nanoparticles(Co-CoSe_(2)@NSeC)is employed as a functional coating layer on commercial separator to improve the performance of LSBs.The well-designed N,Se co-doped nanostructures endow the modified layer with a satisfactory capacity for blocking polysulfides.Both calculations and experiments jointly disclose that the Li_(2)S_(2)to Li_(2)S reaction,including the liquid-solid conversion,was prominently expedited both thermodynamically and electrodynamically.Consequently,the batteries fabricated with Co-CoSe_(2)@NSeC modified separator can deliver a favorable 764.2 mAh g^(−1)with 8.0 C,accompanied by a salient long cycling lifespan(only 0.066%at 1 C and 0.061%under 2 C after 1000 and 2000 cycles),and a desired anode protection.In addition,despite a raised areal loading of 7.53 mg cm^(−2)was introduced,the cells assembled by Co-CoSe_(2)@NSeC@PP are allowed to produce an outstanding initial behavior of 8.71 mAh cm^(−2)under 0.2 C.This work may reinforce further explorations and serve with valuable insights into N,Se dual-doping materials for high-performance LSBs.
基金Project(51504036) supported by the National Natural Science Foundation of ChinaProject(2012CBA01207) supported by the National Basic Research Program of ChinaProject(2011AA03A409) supported by the National High-Tech Research and Development Program of China
文摘The distribution rules of impurities in distilled terbium metal were investigated by vacuum distillation purificationexperiment and theoretical analysis.It is found that Ti impurity in distilled terbium is220mg/kg in the initial stage of the distillationpurification,increases slowly in the middle stage,and increases rapidly in the last stage,reaching2260mg/kg,and the modifiedseparation coefficient of Ti is1/19.02.The diffusion of the impurity Ti in liquid metal can reach a quasi-equilibrium state in theinitial stage of distillation purification and the calculated results agree well with experimental results;the distribution profile ofimpurity Cu is opposite to Ti,being380mg/kg in the initial stage,decreasing linearly to290mg/kg in the last stage,and themodified separation coefficient is17.99,and the theoretical calculated results are inconsistent with the experimental result.
基金Project supported by National Natural Science Foundation of China(51504036)National Basic Research Program of China(2012CBA01207)National High Technology Research and Development Program of China(2011AA03A409)
文摘The distribution rules of impurities contents in distilled metallic dysprosium were researched, and a theoretical analysis was carried out. The research results indicated that, the content of impurity in distilled metal, such as Al and Fe, was lower in the ini-tial stage, increased slowly in the middle stage, and increased rapidly in the last stage during the process of distillation purification. The calculated method of separation coefficient of impurity in crude metal by content of impurity in distilled metal was not suitable for high pure metals, and the modified separation coefficient was proposed, and it equaled 1/6.1 and 1/16.9 for impurity Al and Fe. The physical process of distillation was coincident with that of solidification essentially, and solute re-distribution theory in solidify-ing front could be used to describe the impurity distribution near evaporating surface. In the former stage of distillation purification, the diffusion of impurity in liquid metal could reach a quasi-equilibrium state, the calculated result of impurity content in distilled metal agreed well with experiments. In the latter stage of distillation process, the diffusion rate of impurity in liquid metal decreased, and the content in distilled metal was larger than the calculated result.
基金the support from the National Natural Science Foundation of China(No.21373189)the Science and Technology Department of Henan Province(No.212102210586)the Top-Notch Talents Program of Henan Agricultural University(No.30501035)。
文摘The lithium polysulfide shuttle and sluggish sulfur reaction kinetics still pose significant challenges to lithium-sulfur(Li-S)batteries.The functional plane of Fe-MoSe_(2)@r GO nanohybrid with abundant defects has been designed and applied in Li-S batteries to develop the functional separator and multi-layer sulfur cathode.The cell with a functional separator exhibits a retention capacity of 462 m Ah g^(-1)after the 1000th at 0.5 C and 516 m Ah g^(-1)after the 600th at 0.3 C.Even at low electrolyte conditions(7.0μL_(mgsulfur)^(-1)and 15μL_(mgsulfur)^(-1))under high sulfur loadings(3.46 mg cm^(-2)and 3.73 mg cm^(-2)),the cell still presents high reversible discharge capacities 679 and 762 m Ah g^(-1)after 70 cycles,respectively.Further,at sulfur loadings up to 8.26 and 5.2 mg cm^(-2),the cells assembled with the bi-layers sulfur cathode and the tri-layers sulfur cathode give reversible capacities of 3.3 m Ah cm^(-2)after the 100th cycle and 3.0 m Ah cm^(-2)after the 120th cycle,respectively.This research not only demonstrates that the FeMoSe_(2)@r GO functional plane is successfully designed and applied in Li-S batteries with superior electrochemical performances but also paves the novel way for developing a unique multi-layer cathode technique to enhance and advance the electrochemical behavior of Li-S cells at a high-sulfur-loading cathode under lean electrolyte/sulfur(E/S)ratio.
基金support from the Liao Ning Revitalization Talents Program(No.XLYC1907144)Dalian Youth Science and Technology Star Project Support Program(No.2017RQ104).
文摘In 2011,a new class of 2D materials was discovered;after 2012,they began to be concerned;in 2017,the“gold rush”of the materials was triggered,and they are exactly MXenes.2D MXenes,a new class of transition metal carbides,carbonitrides and nitrides,have become the star and cutting-edge research materials in the field of emerging batteries systems due to their unique 2D structure,abundant surface chemistry,and excellent physical and electrochemical properties.This review focuses on the MXene materials and summarizes the recent advancements in the synthesis techniques and properties,in addition to a detailed discussion on the electrochemical energy storage applications,including alkali-ion(Li^(+),Na^(+),K^(+))storage,lithium-sulfur(Li–S)batteries,sodiumsulfur(Na–S)batteries,and metal anode protection.Special attentions are given to the elaborate design of nano-micro structures of MXenes for the various roles as electrodes,multifunctional components,S hosts,modified separators,and metal anode protective layers.The paper ends with a prospective summary of the promising research directions in terms of synthesis,structure,properties,analysis,and production on MXene materials.
文摘In this paper, the Schr?dinger equation is solved by Modified separation of variables (MSV) method suggested by Pishkoo and Darus. Using this method, Meijer’s G-function solutions are derived in cylindrical coordinate system for quantum particle in cylindrical can. All elementary functions and most of the special functions which are the solution of extensive problems in physics and engineering are special cases of Meijer’s G-functions.
基金supported by the National Natural Science Foundation of China(21863006,51662029,61974082 and 61704096)Youth Science Foundation of Jiangxi Province(20192BAB216001)Key Laboratory of Jiangxi Province for Environment and Energy Catalysis(20181BCD40004)。
文摘The polysulfide shuttling and sluggish redox kinetics,due to the notorious adsorption-catalysis underperformance,are the ultimate obstacles of the practical application of lithium-sulfur(Li-S)batteries.Conventional carbon-based and transition metal compound-based material solutions generally suffer from poor catalysis and adsorption,respectively,despite the performance gain in terms of the other.Herein,we have enhanced polysulfide adsorptioncatalytic capability and protected the Li anode using a complementary bimetallic carbide electrocatalyst,Co3 Mo3 C,modified commercial separator.With this demonstration,the potentials of bimetal compounds,which have been well recognized in other environmental catalysis,are also extended to Li-S batteries.Coupled with this modified separator,a simple cathode(S/Super P composite)can deliver high sulfur utilization,high rate performance,and excellent cycle stability with a low capacity decay rate of^0.034%per cycle at 1 C up to1000 cycles.Even at a high S-loading of 8.0 mg cm^-2 with electrolyte/sulfur ratio=6 m L g^-1,the cathode still exhibits high areal capacity of^6.8 m A h cm^-2.The experimental analysis and the first-principles calculations proved that the bimetallic carbide Co3 Mo3 C provides more binding sites for adsorbing polysulfides and catalyzing the multiphase conversion of sulfur/polysulfide/sulfide than monometallic carbide Mo2 C.Moreover,the modified separator can be reutilized with comparable electrochemical performance.We also showed other bimetallic carbides with similar catalytic effects on Li-S batteries and this material family has great promise indifferent energy electrocatalytic systems.
基金financially supported by the National Natural Science Foundation of China(52072124)Shanghai Municipal Science and Technology Major Project(2018SHZDZX03)+3 种基金the Natural Science Foundation of Shanghai(20ZR1414900)the Leading Talents in Shanghai in2018the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learningthe 111 Project(B14018)。
文摘The intrinsic sluggish conversion kinetics and severe shuttle effect in lithium-sulfur(Li-S)batteries are responsible for their poor reversible capacity and cycling longevity,which have greatly hindered their practical applications.To address these drawbacks,herein,we design and construct a heterostructured Ni/Ni_(2)P embedded in a mesoporous carbon nanosphere composite(Ni/Ni_(2)P-MCN)for boosting polysulfide catalytic conversion in Li-S batteries.The Ni/Ni_(2)PMCN-modified separator could not only prevent the shuttle effect significantly through abundant chemical adsorptive sites,but also demonstrate superior catalytic reactivities for the conversion of polysulfides.More importantly,the conductive carbon matrix with an exposed mesoporous structure can serve as an effective physical barrier to accommodate deposited insoluble Li_(2)S.Consequently,the cells with the Ni/Ni_(2)P-MCN-modified separator exhibit greatly boosted rate capability(431 mA h g^(-1) at 5 C)and cycling stability(a capacity decay of 0.031% per cycle after 1500 cycles).Even at an enhanced sulfur loading of 4.2 mg cm^(-2),a stable and superior areal capacity(about 3.5 mA h cm^(-2))has been demonstrated.We envision that the unique Ni/Ni_(2)P heterostructure in the porous carbon matrix could offer great potential for highperformance and sustained energy storage devices.
基金support from the National Natural Science Foundation of China(No.52090034)the Higher Education Discipline Innovation Project(No.B12015).
文摘Lithium-sulfur(Li-S)batteries are highly regarded as the next-generation high-energy-density secondary batteries due to their high capacity and large theoretical energy density.However,the practical application of these batteries is hindered mainly by the polysulfide shuttle issue.Herein,we designed and synthesized a new lithium sulfonylimide covalent organic framework(COF)material(COF-LiSTFSI,LiSTFSI=lithium(4-styrenesulfonyl)(trifluoromethanesulfonyl)imide),and further used it to modify the common polypropylene(PP)separator of Li-S batteries.The COF-LiSTFSI with sulfonylimide anion groups features stronger electronegativity,thus can effectively facilitate the lithium ion conduction while significantly suppress the diffusion of polysulfides via the electrostatic interaction.Compared with the unmodified PP separator,the COF-LiSTFSI modified separator results in a high ionic conductivity(1.50 mS·cm^(−1))and Li+transference number(0.68).Consequently,the Li-S battery using the COF-LiSTFSI modified separator achieves a high capacity of 1229.7 mAh·g^(−1)at 0.2 C and a low decay rate of only 0.042%per cycle after 1000 cycles at 1 C,compared with those of 941.5 mAh·g^(−1)and 0.061%using the unmodified PP separator,respectively.These results indicate that by choosing suitable functional groups,an effective strategy for COF-modified separators could be developed for high-performance Li-S batteries.
