Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrol...Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrolyte interface (SEI) lead to rapid capacity fading and low rate performance.Herein,we report Si nitride (SiN) comprising stoichiometric Si_(3)N_(4) and Li-active anazotic SiN_(x) coated porous Si (p-Si@SiN)for high-performance anodes in LIBs.The ant-nest-like porous Si consisting of 3D interconnected Si nanoligaments and bicontinuous nanopores prevents pulverization and accommodates volume expansion during cycling.The Si_(3)N_(4) offers mechanically protective coating to endow highly structural integrity and inhibit superfluous formation of SEI.The fast ion conducting Li_(3)N generated in situ from lithiation of active SiN_(x) facilitates Li ion transport.Consequently,the p-Si@SiN anode has appealing electrochemical properties such as a high capacity of 2180 mAh g^(-1)at 0.5 A g^(-1) with 84%capacity retention after 200cycles and excellent rate capacity with discharge capacity of 721 mAh g^(-1) after 500 cycles at 5.0 A g^(-1).This work provides insights into the rational design of active/inactive nanocoating on Si-based anode materials for fast-charging and highly stable LIBs.展开更多
Polybenzimidazole(PBI)is a kind of proton transport membrane material,and its ion conductivity is a key factor affecting its application in vanadium redox flow batteries(VRFBs).The casting solvent of PBI has a signifi...Polybenzimidazole(PBI)is a kind of proton transport membrane material,and its ion conductivity is a key factor affecting its application in vanadium redox flow batteries(VRFBs).The casting solvent of PBI has a significant influence on the acid doping level of PBI membranes which is closely related to ionic conductivity.In this paper,3,3′-diaminobenzidine(DABz)and 4,4′-Dicarboxydiphenylether(DCDPE)were used as raw materials by solution condensation to prepare the PBI with ether bond groups.The chemical structure of PBI was determined by1H NMR and FT-IR,and the prepared PBI had good solubility which can be dissolved in a variety of solvents.The PBI proton exchange membranes were prepared by solution coating with 5 different solvents of N,N-dimethylformamide(DMF),N,N-dimethylacetamide(DMAc),dimethyl sulfoxide(DMSO),1-methyl-2-pyrrolidone(NMP),methane sulfonic acid(MSA).The effects of different solvents on the ion conductivity and physicochemical properties were discussed in detail.The results showed that the PBI membrane prepared by using MSA as solvent(the PBI+MSA membrane)exhibits high water uptake,acid doping level and low vanadium ion permeability.The VRFB assembled with the PBI+MSA membrane exhibited higher coulombic efficiency(CE)99.87%and voltage efficiency(VE)84.50%than that of the commercial Nafion115 membrane at100 m A·cm-2,and after 480 cycles,the EE value can still be maintained at 83.73%.The self-discharge time of a single battery was recorded to be as long as 1000 h.All experimental data indicated that MSA is the best solvent for casting PBI membrane.展开更多
Materials Lao.8Sro.2Gao.83Mgo.17_xCox03_6 with x = 0, 0.05, 0.085, 0.10, and 0.15 are synthesized by laser rapid solidification. It is shown that the samples prepared by laser rapid solidification give rise to unique ...Materials Lao.8Sro.2Gao.83Mgo.17_xCox03_6 with x = 0, 0.05, 0.085, 0.10, and 0.15 are synthesized by laser rapid solidification. It is shown that the samples prepared by laser rapid solidification give rise to unique spear-like or leaf-like microstructures which are orderly arranged and densely packed. Their electrical properties each show a general depen dence of the Co content and the total conductivities of Lao.8Sro.2Gao.83Mgo.085Coo.08503_6 prepared by laser rapid solidification are measured to be 0.067, 0.124, and 0.202 S.cm-1 at 600, 700, and 800 ℃, respectively, which are much higher than by conventional solid state reactions. Moreover, the electrical conductivities each as a function of the oxy gen partial pressure are also measured. It is shown that the samples with the Co content values 〈 8.5 mol% each exhibit basically ionic conduction while those for Co content values 〉 10 mol % each show ionic mixed electronic conduction under oxygen partial pressures from 10-16 atm （1 atm = 1.01325 x 105 Pa） to 0.98 atm. The improved ionic conductivity of Lao.sSro.2Gao.83Mgo.085Coo.08503 prepared by laser rapid solidification compared with by solid state reactions is attributed to the unique microstructure of the sample generated during laser rapid solidification.展开更多
A theoretical prediction of ion conductivity for solid state HfO2 is carried out in analogy to ZrO2 based on the density functional calculation. Geometric and electronic structures of pure bulks exhibit similarity for...A theoretical prediction of ion conductivity for solid state HfO2 is carried out in analogy to ZrO2 based on the density functional calculation. Geometric and electronic structures of pure bulks exhibit similarity for the two materials. Negative formation enthalpy and negative vacancy formation energy are found for YSH （yttria-stabilized hafnia） and YSZ （yttria- stabilized zirconia）, suggesting the stability of both materials. Low activation energies （below 0.7 eV） of diffusion are found in both materials, and YSH＇s is a little higher than that of YSZ. In addition, for both HfO2 and ZrO2, the supercells with native oxygen vacancies are also studied. The so-called defect states are observed in the supercells with neutral and ＋1 charge native vacancy but not in the ＋2 charge one. It can give an explanation to the relatively lower activation energies of yttria-doped oxides and ＋2 charge vacancy supercells. A brief discussion is presented to explain the different YSH ion conductivities in the experiment and obtained by us, and we attribute this to the different ion vibrations at different temperatures.展开更多
Because of its superior safety and excellent processability,solid polymer electrolytes(SPEs)have attracted widespread attention.In lithium based batteries,SPEs have great prospects in replacing leaky and flammable liq...Because of its superior safety and excellent processability,solid polymer electrolytes(SPEs)have attracted widespread attention.In lithium based batteries,SPEs have great prospects in replacing leaky and flammable liquid electrolytes.However,the low ionic conductivity of SPEs cannot meet the requirements of high energy density systems,which is also an important obstacle to its practical application.In this respect,escalating charge carriers(i.e.Li^(+))and Li^(+)transport paths are two major aspects of improving the ionic conductivity of SPEs.This article reviews recent advances from the two perspectives,and the underlying mechanism of these proposed strategies is discussed,including increasing the Li^(+)number and optimizing the Li^(+)transport paths through increasing the types and shortening the distance of Li^(+)transport path.It is hoped that this article can enlighten profound thinking and open up new ways to improve the ionic conductivity of SPEs.展开更多
The physical expression of electrical conductivity of ternary glass can be obtained by the physical scattering theory of conducting ions by the defects in the glass. The scattering area of ion by the nucleus is given ...The physical expression of electrical conductivity of ternary glass can be obtained by the physical scattering theory of conducting ions by the defects in the glass. The scattering area of ion by the nucleus is given by the law of Rutherford in atomic physics. By this theory, the physical meaning of the microprocess of ionic conductivity of ternary glass is apparent.展开更多
A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety problems.Our study addresses the...A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety problems.Our study addresses these problems by proposing a modified polyrotaxane(mPR)-based solid polymer electrolyte(SPE)design that simultaneously mitigates solvent-related problems and improves conductivity.mPR-SPE exhibits high ion conductivity(2.8×10^(−3)S cm^(−1)at 25℃)through aligned ion conduction pathways and provides electrode protection ability through hydrophobic chain dispersion.Integrating this mPR-SPE into solid-state LOBs resulted in stable potentials over 300 cycles.In situ Raman spectroscopy reveals the presence of an LiO_(2)intermediate alongside Li_(2)O_(2)during oxygen reactions.Ex situ X-ray diffraction confirm the ability of the SPE to hinder the permeation of oxygen and moisture,as demonstrated by the air permeability tests.The present study suggests that maintaining a low residual solvent while achieving high ionic conductivity is crucial for restricting the sub-reactions of solid-state LOBs.展开更多
The ion conductivity of a solid-state ion conductor generally increases exponentially upon reduction in ionmigration barrier.For prevalent cathode material LiCoO_(2),the room-temperature ion conductivity and migration...The ion conductivity of a solid-state ion conductor generally increases exponentially upon reduction in ionmigration barrier.For prevalent cathode material LiCoO_(2),the room-temperature ion conductivity and migrationbarrier are respectively around 10^(−4)S/cm and 0.3 eV.In this Letter,through first-principles calculations we predictthe existence of 1D superionicity as the Li ions in O_(2)LiCoO_(2)are transformed into Zn_(0.5)CoO_(2)or Li_(0.5)CoO_(2)via cation-exchange reaction or deintercalation.The ion migration barriers(0.01-0.02 eV)even lower than roomtemperature∼𝑘B𝑇are reduced by more than an order of magnitude compared with LiCoO_(2),which are facilitatedby facile transition of mobile ions between two coordination configurations.The room-temperature ion conductivityis estimated to be over 50 S/cm,enhanced by 2-3 orders of magnitude compared with the current highestreported value.Such unprecedented superionicity may also exist in other similar layered ion conductors,whichmay lead to technical advances and exotic effects such as ultrafast ion batteries and quantized ferroelectricity.展开更多
Regulating lithium(Li)plating/stripping behavior in three-dimensional(3D)conductive scaffolds is critical to stabilizing Li metal batteries(LMBs).Surface protrusions and roughness in these scaffolds can induce uneven ...Regulating lithium(Li)plating/stripping behavior in three-dimensional(3D)conductive scaffolds is critical to stabilizing Li metal batteries(LMBs).Surface protrusions and roughness in these scaffolds can induce uneven distributions of the electric fields and ionic concentrations,forming“hot spots.”Hot spots may cause uncontrollable Li dendrites growth,presenting significant challenges to the cycle stability and safety of LMBs.To address these issues,we construct a Li ionic conductive-dielectric gradient bifunctional interlayer(ICDL)onto a 3D Li-injected graphene/carbon nanotube scaffold(LGCF)via in situ reaction of exfoliated hexagonal boron nitride(fhBN)and molten Li.Microscopic and spectroscopic analyses reveal that ICDL consists of fhBN-rich outer layer and inner layer enriched with Li_(3)N and Li-boron composites(Li-B).The outer layer utilizes dielectric properties to effectively homogenize the electric field,while the inner layer ensures high Li ion conductivity.Moreover,DFT calculations indicate that ICDL can effectively adsorb Li and decrease the Li diffusion barrier,promoting enhanced Li ion transport.The modulation of Li kinetics by ICDL increases the critical length of the Li nucleus,enabling suppression of Li dendrite growth.Attributing to these advantages,the ICDL-coated LGCF(ICDL@LGCF)demonstrates impressive long-term cycle performances in both symmetric cells and full cells.展开更多
The practical application of lithium(Li)metal batteries(LMBs)faces challenges due to the irreversible Li deposition/dissolution process,which promotes Li dendrite growth with severe parasitic reactions during cycling....The practical application of lithium(Li)metal batteries(LMBs)faces challenges due to the irreversible Li deposition/dissolution process,which promotes Li dendrite growth with severe parasitic reactions during cycling.To address these issues,achieving uniform Li‐ion flux and improving Li‐ion conductivity of the separator are the top priorities.Herein,a separator(PCELS)with enhanced Li‐ion conductivity,composed of polymer,ceramic,and electrically conductive carbon,is proposed to facilitate fast Li‐ion transport kinetics and increase Li deposition uniformity of the LMBs.The PCELS immobilizes PF6–anions with high adsorption energies,leading to a high Li‐ion transference number.Simultaneously,the PCELS shows excellent electrolyte wettability on both its sides,promoting rapid ion transport.Moreover,the electrically conductive carbon within the PCELS provides additional electron transport channels,enabling efficient charge transfer and uniform Li‐ion flux.With these advantages,the PCELS achieves rapid Li‐ion transport kinetics and uniform Li deposition,demonstrating excellent cycling stability over 100 cycles at a high current density of 12.0 mA cm^(-2).Furthermore,the PCELS shows stable cycling performances in Li–S cell tests and delivers an excellent capacity retention of 95.45%in the Li|LiFePO_(4) full‐cell test with a high areal capacity of over 5.5 mAh cm^(-2).展开更多
Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and t...Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported.The samples were characterized by thermal analysis(TG-DSC) ,X-ray diffraction(XRD) and scanning electron micrograph(SEM) . The apatite was obtained at 800°C,a relatively low temperature in comparison to 1500°C with the conventional solid-state method.The ceramic pellets sintered at 1200°C for 5 h showed a higher relative density than La9.33Si6O26 pellets sintered at 1400°C for 20 h.The conductivities of samples were measured by electrochemical impedance spectroscopy.The conductivity was improved with the increase of V-dopant content on La site.展开更多
A method for rapid and simultaneous determination of multiple pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection was developed.Chromatographic separations were performed on a c...A method for rapid and simultaneous determination of multiple pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection was developed.Chromatographic separations were performed on a cation exchange column using ethylenediamine-acetonitrile as the mobile phase.The effects of chromatographic column and the mobile phase,as well as the column temperature on the retention of the cations were investigated.The retention rules of the cations under different chromatographic conditions were formulated.The retention of the cations followed the carbon number rule.The method has been successfully applied to the determination of three ionic liquids synthesized by a chemical laboratory.展开更多
Polyparaphenylene(PPP) is prepared by AlCl 3-CuCl 2 catalysts with benzene as the monomer and is doped by chemical method and N + ion implantation. The influences of the concentration, temperature and time of chemi...Polyparaphenylene(PPP) is prepared by AlCl 3-CuCl 2 catalysts with benzene as the monomer and is doped by chemical method and N + ion implantation. The influences of the concentration, temperature and time of chemical doping and the dose, energy and temperature of ion implantation, on PPP conductivity are investigated. The results showed that the conductivity of PPP can be improved 4～5 orders of magnitude by ion implantation and the conductivity of PPP can reach about 0.11 S·cm -1 by chemical doping. The comparison of stability of the material conductive behavior by using the two doping methods is presented. It shows that ion implantation is better than chemical doping in stabilizing the electric conductive behavior for the material.展开更多
Lithium plating/stripping occurs at the a node/electrolyte interface which involves the flow of electrons from the current collector and the migration of lithium ions from the solid-electrolyte interphase(SEI).The dua...Lithium plating/stripping occurs at the a node/electrolyte interface which involves the flow of electrons from the current collector and the migration of lithium ions from the solid-electrolyte interphase(SEI).The dual continuous rapid transport of interfacial electron/ion is required for homogeneous Li deposition.Herein,we propose a strategy to improve the Li metal anode performance by rationally regulating the interfacial electron density and Li ion transport through the SEI film.This key technique involves decreasing the interfacial oxygen density of biomass-derived carbon host by regulating the arrangement of the celluloses precursor fibrils.The higher specific surface area and lower interfacial oxygen density decrease the local current density and ensure the formation of thin and even SEI film,which stabilized Li^(+)transfer through the Li/electrolyte interface.Moreover,the improved graphitization and the interconnected conducting network enhance the surface electronegativity of carbon and enable uninterruptible electron conduction.The result is continuous and rapid coupled interfacial electron/ion transport at the anode/electrolyte reaction interface,which facilitates uniform Li deposition and improves Li anode performance.The Li/C anode shows a high initial Coulombic efficiency of 98%and a long-term lifespan of over 150cycles at a practical low N/P(negative-to-positive)ratio of 1.44 in full cells.展开更多
Polyethylene oxide(PEO)-based electrolytes are considered as one of the most promising solid-state electrolytes for next-generation lithium batteries with high safety and energy density;however,the drawbacks such as i...Polyethylene oxide(PEO)-based electrolytes are considered as one of the most promising solid-state electrolytes for next-generation lithium batteries with high safety and energy density;however,the drawbacks such as insufficient ion conductance,mechanical strength and electrochemical stability hinder their applications in metallic lithium batteries.To enhance their overall properties,flexible and thin composite polymer electrolyte(CPE)membranes with 3D continuous aramid nanofiber(ANF)–Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)nanoparticle hybrid frameworks are facilely prepared by filling PEO–Li TFSI in the 3D nanohybrid scaffolds via a solution infusion way.The construction of the 3D continuous nanohybrid networks can effectively inhibit the PEO crystallization,facilitate the lithium salt dissociation and meanwhile increase the fast-ion transport in the continuous LATP electrolyte phase,and thus greatly improving the ionic conductivity(~3 times that of the pristine one).With the integration of the 3D continuity and flexibility of the 3D ANF networks and the thermostability of the LATP phase,the CPE membranes also show a wider electrochemical window(~5.0 V vs.4.3 V),higher tensile strength(~4–10times that of the pristine one)and thermostability,and better lithium dendrite resistance capability.Furthermore,the CPE-based Li FePO_(4)/Li cells exhibit superior cycling stability(133 m Ah/g after 100 cycles at 0.3 C)and rate performance(100 m Ah/g at 1 C)than the pristine electrolyte-based cell(79 and 29m Ah/g,respectively).This work offers an important CPE design criteria to achieve comprehensivelyupgraded solid-state electrolytes for safe and high-energy metal battery applications.展开更多
Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) ...Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) (PVA) at 90 degree C and act as plasticizer in the blend films cast from the solution. Only a glass transition temperature is observed for all these blends indicating the formation of compatible blends from these polyesters with PVA. These blends exhibit manifold characteristics such as ionic conductivity, complex formation with metal ions, absorption of moisture and color changes. The electric conductivity of the copolyesters and blends is in the range of 10** minus **6 Scm** minus **1. The blends with PVA forms complexes with Cu**2** plus and Co**2** plus . The coordination structure with two chelate rings is suggested for these polymer blend/metal complexes. (Author abstract) 10 Refs.展开更多
A series of brominated polynorbornene derivatives,including bulky steric hydrophobic groups and highly physical and chemical stable backbones,were synthesized via ring-opening metathesis polymerization and post-functi...A series of brominated polynorbornene derivatives,including bulky steric hydrophobic groups and highly physical and chemical stable backbones,were synthesized via ring-opening metathesis polymerization and post-functionalized with trimethylammonium(QA),N-methylimidazole(Im),N-methylpyrrolidinium(Pyr)or N-methylpiperidinium(Pip)to construct the entire anion exchange membranes(AEMs).Benefited from prominent phase-separated morphology,PBO-x%-y(x=66,68,70;y=QA,Im,Pyr,Pip)AEMs with ion exchange capacity(IEC)approaching 2.0 meq·g^(−1)exhibited super high hydroxide conductivities.Thereinto,PBO-70%-Pip possessed the highest hydroxide conductivity of 137.3 mS·cm^(−1)at 80℃Moreover,all membranes exhibit low swelling ratio(SR)(the SR of PBO-66%-QA was just 8.6%at 80℃).That is,bulky steric hydrophobic groups play a crucial role in balancing the high hydroxide conductivity and low SR in AEMs.Furthermore,three AEMs(PBO-66%-QA,PBO-68%-Pyr,PBO-70%-Pip)showed good alkaline stability after immersion into 1.0 mol/L NaOH aqueous solution at 80℃for 480 h without any degradation.展开更多
Green method for preparation of ion-conducting membranes(ICM) based on bacterial cellulose nanofibers(CNF) modified by a copolymer of sodium acrylate and 2-acrylamido-2-methylpropanesulfonic acid was elaborated. FTIR ...Green method for preparation of ion-conducting membranes(ICM) based on bacterial cellulose nanofibers(CNF) modified by a copolymer of sodium acrylate and 2-acrylamido-2-methylpropanesulfonic acid was elaborated. FTIR and NMR data confirmed grafting of polyacrylate onto cellulose surface. Formation of porous structure of the ICM was controlled by SEM and AFM. The maximal ionic conductivity of the membranes reaches 1.5 and 3.1 mS·cm^(-1)(60 ℃ and 98% relative humidity) when they are saturated with water or H_2SO_4(1 mol·L^(-1)) electrolyte,respectively. Prepared ICM was tested as a separator in a symmetrical supercapacitor with electrodes based on polyaniline hydrogel. The assembled cell demonstrate ability to operate at high current density up to 100 A·g^(-1) maintaining specific capacitance 165 F·g^(-1). Maximal specific capacitance of 289 F·g^(-1) was achieved at current density 1 A·g^(-1). Retaining of 90% of initial capacitance after 10000 of charge-discharge cycles proves high electrochemical stability of prepared ICM.展开更多
Herein, we developed novel silicon-carbon-nitrogen （SiCN） composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperature...Herein, we developed novel silicon-carbon-nitrogen （SiCN） composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperatures of 700 ℃, 1000 ℃ and 1300 ℃, the SiCN composites prepared at 1000 ℃ showed the highest capacity with outstanding battery cycle life by cyclic voltammetry and electrochemical impedance spectroscopy. Such good battery and electrochemical performances should be attributed to a proper ratio of carbon and nitrogen or oxygen in the SiCN composites. Furthermore, our SiCN electrode possessed better lithium ion conductivity than pure silicon nanoparticles. This work demonstrates that polymer-derived composites are among the promising strategies to achieve highly stable silicon anodes for rechargeable batteries.展开更多
Humidity measurement in a very low moisture atmosphere was studied by using solid electrolyte film coated with porous electrodes,considering its application to the moisture monitoring of SF_6 gas-insulated high voltag...Humidity measurement in a very low moisture atmosphere was studied by using solid electrolyte film coated with porous electrodes,considering its application to the moisture monitoring of SF_6 gas-insulated high voltage instruments such as gas-insulated switchgear (GIS) and gas circuit breakers (GCBs).Compared to the AC impedance values measured in an ambient atmosphere where the moisture atmosphere is far higher than that in these instruments,considerably large impedance values were obtained in a very low moisture atmosphere.The impedance was systematically measured in accordance with the conditions of these instruments whose moisture contents were less than 1 000×10^(-6).A good correlation was obtained between the impedance values and the moisture contents.The frequency characteristics of the impedance were analyzed based on a conventional equivalent circuit where a number of CR circuits were connected in series.Considering the dielectric relaxation of each circuit,it was found that the frequency characteristics of the impedance can be explained by the equivalent circuit. Two semicircles were clearly obtained in the Cole-Cole impedance plot which are thought to reflect the impedance characteristics of the film and the electrodes.The AC impedance can be a good indicator of the moisture content of SF_6 gas-insulated high voltage instruments.展开更多
基金financially supported by the National Natural Science Foundation of China (U2004210, 51974208, U2003130, 21875080, 52002297)the Outstanding Youth Foundation of Natural Science Foundation of Hubei Province (2020CFA099)+2 种基金the Special Project of Central Government for Local Science and Technology Development of Hubei Province (2019ZYYD024)the Innovation group of Natural Science Foundation of Hubei Province (2019CFA020)the City University of Hong Kong Strategic Research Grants (7005505)。
文摘Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrolyte interface (SEI) lead to rapid capacity fading and low rate performance.Herein,we report Si nitride (SiN) comprising stoichiometric Si_(3)N_(4) and Li-active anazotic SiN_(x) coated porous Si (p-Si@SiN)for high-performance anodes in LIBs.The ant-nest-like porous Si consisting of 3D interconnected Si nanoligaments and bicontinuous nanopores prevents pulverization and accommodates volume expansion during cycling.The Si_(3)N_(4) offers mechanically protective coating to endow highly structural integrity and inhibit superfluous formation of SEI.The fast ion conducting Li_(3)N generated in situ from lithiation of active SiN_(x) facilitates Li ion transport.Consequently,the p-Si@SiN anode has appealing electrochemical properties such as a high capacity of 2180 mAh g^(-1)at 0.5 A g^(-1) with 84%capacity retention after 200cycles and excellent rate capacity with discharge capacity of 721 mAh g^(-1) after 500 cycles at 5.0 A g^(-1).This work provides insights into the rational design of active/inactive nanocoating on Si-based anode materials for fast-charging and highly stable LIBs.
基金the National Natural Science Foundation of China(No.21878317)the Beijing National Science Foundation(L172047)for financial support。
文摘Polybenzimidazole(PBI)is a kind of proton transport membrane material,and its ion conductivity is a key factor affecting its application in vanadium redox flow batteries(VRFBs).The casting solvent of PBI has a significant influence on the acid doping level of PBI membranes which is closely related to ionic conductivity.In this paper,3,3′-diaminobenzidine(DABz)and 4,4′-Dicarboxydiphenylether(DCDPE)were used as raw materials by solution condensation to prepare the PBI with ether bond groups.The chemical structure of PBI was determined by1H NMR and FT-IR,and the prepared PBI had good solubility which can be dissolved in a variety of solvents.The PBI proton exchange membranes were prepared by solution coating with 5 different solvents of N,N-dimethylformamide(DMF),N,N-dimethylacetamide(DMAc),dimethyl sulfoxide(DMSO),1-methyl-2-pyrrolidone(NMP),methane sulfonic acid(MSA).The effects of different solvents on the ion conductivity and physicochemical properties were discussed in detail.The results showed that the PBI membrane prepared by using MSA as solvent(the PBI+MSA membrane)exhibits high water uptake,acid doping level and low vanadium ion permeability.The VRFB assembled with the PBI+MSA membrane exhibited higher coulombic efficiency(CE)99.87%and voltage efficiency(VE)84.50%than that of the commercial Nafion115 membrane at100 m A·cm-2,and after 480 cycles,the EE value can still be maintained at 83.73%.The self-discharge time of a single battery was recorded to be as long as 1000 h.All experimental data indicated that MSA is the best solvent for casting PBI membrane.
基金supported by the National Natural Science Foundation of China(Grant No.10974183)the Fund for Science and Technology Innovation Team of Zhengzhou City,China(Grant No.2011-3)the Postdoctoral Research Sponsorship in Henan Province,China(Grant No.2011002)
文摘Materials Lao.8Sro.2Gao.83Mgo.17_xCox03_6 with x = 0, 0.05, 0.085, 0.10, and 0.15 are synthesized by laser rapid solidification. It is shown that the samples prepared by laser rapid solidification give rise to unique spear-like or leaf-like microstructures which are orderly arranged and densely packed. Their electrical properties each show a general depen dence of the Co content and the total conductivities of Lao.8Sro.2Gao.83Mgo.085Coo.08503_6 prepared by laser rapid solidification are measured to be 0.067, 0.124, and 0.202 S.cm-1 at 600, 700, and 800 ℃, respectively, which are much higher than by conventional solid state reactions. Moreover, the electrical conductivities each as a function of the oxy gen partial pressure are also measured. It is shown that the samples with the Co content values 〈 8.5 mol% each exhibit basically ionic conduction while those for Co content values 〉 10 mol % each show ionic mixed electronic conduction under oxygen partial pressures from 10-16 atm （1 atm = 1.01325 x 105 Pa） to 0.98 atm. The improved ionic conductivity of Lao.sSro.2Gao.83Mgo.085Coo.08503 prepared by laser rapid solidification compared with by solid state reactions is attributed to the unique microstructure of the sample generated during laser rapid solidification.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10647008 and 50971099)the Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20096101110017)
文摘A theoretical prediction of ion conductivity for solid state HfO2 is carried out in analogy to ZrO2 based on the density functional calculation. Geometric and electronic structures of pure bulks exhibit similarity for the two materials. Negative formation enthalpy and negative vacancy formation energy are found for YSH （yttria-stabilized hafnia） and YSZ （yttria- stabilized zirconia）, suggesting the stability of both materials. Low activation energies （below 0.7 eV） of diffusion are found in both materials, and YSH＇s is a little higher than that of YSZ. In addition, for both HfO2 and ZrO2, the supercells with native oxygen vacancies are also studied. The so-called defect states are observed in the supercells with neutral and ＋1 charge native vacancy but not in the ＋2 charge one. It can give an explanation to the relatively lower activation energies of yttria-doped oxides and ＋2 charge vacancy supercells. A brief discussion is presented to explain the different YSH ion conductivities in the experiment and obtained by us, and we attribute this to the different ion vibrations at different temperatures.
基金supported by the National Natural Science Foundation of China(51872196)the Natural Science Foundation of Tianjin,China(17JCJQJC44100)the National Postdoctoral Program for Innovative Talents,China(BX20190232)。
文摘Because of its superior safety and excellent processability,solid polymer electrolytes(SPEs)have attracted widespread attention.In lithium based batteries,SPEs have great prospects in replacing leaky and flammable liquid electrolytes.However,the low ionic conductivity of SPEs cannot meet the requirements of high energy density systems,which is also an important obstacle to its practical application.In this respect,escalating charge carriers(i.e.Li^(+))and Li^(+)transport paths are two major aspects of improving the ionic conductivity of SPEs.This article reviews recent advances from the two perspectives,and the underlying mechanism of these proposed strategies is discussed,including increasing the Li^(+)number and optimizing the Li^(+)transport paths through increasing the types and shortening the distance of Li^(+)transport path.It is hoped that this article can enlighten profound thinking and open up new ways to improve the ionic conductivity of SPEs.
文摘The physical expression of electrical conductivity of ternary glass can be obtained by the physical scattering theory of conducting ions by the defects in the glass. The scattering area of ion by the nucleus is given by the law of Rutherford in atomic physics. By this theory, the physical meaning of the microprocess of ionic conductivity of ternary glass is apparent.
基金supported by a National Research Foundation of Korea(NRF)Grant funded by the Ministry of Science and ICT(2021R1A2C1014294,2022R1A2C3003319)the BK21 FOUR(Fostering Outstanding Universities for Research)through the National Research Foundation(NRF)of Korea.
文摘A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety problems.Our study addresses these problems by proposing a modified polyrotaxane(mPR)-based solid polymer electrolyte(SPE)design that simultaneously mitigates solvent-related problems and improves conductivity.mPR-SPE exhibits high ion conductivity(2.8×10^(−3)S cm^(−1)at 25℃)through aligned ion conduction pathways and provides electrode protection ability through hydrophobic chain dispersion.Integrating this mPR-SPE into solid-state LOBs resulted in stable potentials over 300 cycles.In situ Raman spectroscopy reveals the presence of an LiO_(2)intermediate alongside Li_(2)O_(2)during oxygen reactions.Ex situ X-ray diffraction confirm the ability of the SPE to hinder the permeation of oxygen and moisture,as demonstrated by the air permeability tests.The present study suggests that maintaining a low residual solvent while achieving high ionic conductivity is crucial for restricting the sub-reactions of solid-state LOBs.
基金supported by the National Natural Science Foundation of China(Grant No.22073034)。
文摘The ion conductivity of a solid-state ion conductor generally increases exponentially upon reduction in ionmigration barrier.For prevalent cathode material LiCoO_(2),the room-temperature ion conductivity and migrationbarrier are respectively around 10^(−4)S/cm and 0.3 eV.In this Letter,through first-principles calculations we predictthe existence of 1D superionicity as the Li ions in O_(2)LiCoO_(2)are transformed into Zn_(0.5)CoO_(2)or Li_(0.5)CoO_(2)via cation-exchange reaction or deintercalation.The ion migration barriers(0.01-0.02 eV)even lower than roomtemperature∼𝑘B𝑇are reduced by more than an order of magnitude compared with LiCoO_(2),which are facilitatedby facile transition of mobile ions between two coordination configurations.The room-temperature ion conductivityis estimated to be over 50 S/cm,enhanced by 2-3 orders of magnitude compared with the current highestreported value.Such unprecedented superionicity may also exist in other similar layered ion conductors,whichmay lead to technical advances and exotic effects such as ultrafast ion batteries and quantized ferroelectricity.
基金the financial support from the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2023R1A2C2007699 and 2022R1A6A1A0306303912)the Nano Material Technology Development Program through the NRF funded by the Ministry of Science and ICT (NRF-2015M3A7B6027970)the Technology Innovation Program by the Ministry of Trade, Industry & Energy (RS-202300236794)
文摘Regulating lithium(Li)plating/stripping behavior in three-dimensional(3D)conductive scaffolds is critical to stabilizing Li metal batteries(LMBs).Surface protrusions and roughness in these scaffolds can induce uneven distributions of the electric fields and ionic concentrations,forming“hot spots.”Hot spots may cause uncontrollable Li dendrites growth,presenting significant challenges to the cycle stability and safety of LMBs.To address these issues,we construct a Li ionic conductive-dielectric gradient bifunctional interlayer(ICDL)onto a 3D Li-injected graphene/carbon nanotube scaffold(LGCF)via in situ reaction of exfoliated hexagonal boron nitride(fhBN)and molten Li.Microscopic and spectroscopic analyses reveal that ICDL consists of fhBN-rich outer layer and inner layer enriched with Li_(3)N and Li-boron composites(Li-B).The outer layer utilizes dielectric properties to effectively homogenize the electric field,while the inner layer ensures high Li ion conductivity.Moreover,DFT calculations indicate that ICDL can effectively adsorb Li and decrease the Li diffusion barrier,promoting enhanced Li ion transport.The modulation of Li kinetics by ICDL increases the critical length of the Li nucleus,enabling suppression of Li dendrite growth.Attributing to these advantages,the ICDL-coated LGCF(ICDL@LGCF)demonstrates impressive long-term cycle performances in both symmetric cells and full cells.
基金supported by Ministry of Science and ICT,South Korea(RS‐2024‐00407282)National Research Foundation of Korea(RS‐2024‐00408156).
文摘The practical application of lithium(Li)metal batteries(LMBs)faces challenges due to the irreversible Li deposition/dissolution process,which promotes Li dendrite growth with severe parasitic reactions during cycling.To address these issues,achieving uniform Li‐ion flux and improving Li‐ion conductivity of the separator are the top priorities.Herein,a separator(PCELS)with enhanced Li‐ion conductivity,composed of polymer,ceramic,and electrically conductive carbon,is proposed to facilitate fast Li‐ion transport kinetics and increase Li deposition uniformity of the LMBs.The PCELS immobilizes PF6–anions with high adsorption energies,leading to a high Li‐ion transference number.Simultaneously,the PCELS shows excellent electrolyte wettability on both its sides,promoting rapid ion transport.Moreover,the electrically conductive carbon within the PCELS provides additional electron transport channels,enabling efficient charge transfer and uniform Li‐ion flux.With these advantages,the PCELS achieves rapid Li‐ion transport kinetics and uniform Li deposition,demonstrating excellent cycling stability over 100 cycles at a high current density of 12.0 mA cm^(-2).Furthermore,the PCELS shows stable cycling performances in Li–S cell tests and delivers an excellent capacity retention of 95.45%in the Li|LiFePO_(4) full‐cell test with a high areal capacity of over 5.5 mAh cm^(-2).
基金Supported by the Joint Funds of NSFC-Guangdong of China(U0834004)the Natural Science Foundation of Guangdong Province(06025657)
文摘Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported.The samples were characterized by thermal analysis(TG-DSC) ,X-ray diffraction(XRD) and scanning electron micrograph(SEM) . The apatite was obtained at 800°C,a relatively low temperature in comparison to 1500°C with the conventional solid-state method.The ceramic pellets sintered at 1200°C for 5 h showed a higher relative density than La9.33Si6O26 pellets sintered at 1400°C for 20 h.The conductivities of samples were measured by electrochemical impedance spectroscopy.The conductivity was improved with the increase of V-dopant content on La site.
基金supported by the Natural Science Foundation of Heilongjiang Province(No.B200909)the Program for Scientific and Technological Innovation Team Construction in Universities of Heilongjiang Province(No.2011TD010)
文摘A method for rapid and simultaneous determination of multiple pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection was developed.Chromatographic separations were performed on a cation exchange column using ethylenediamine-acetonitrile as the mobile phase.The effects of chromatographic column and the mobile phase,as well as the column temperature on the retention of the cations were investigated.The retention rules of the cations under different chromatographic conditions were formulated.The retention of the cations followed the carbon number rule.The method has been successfully applied to the determination of three ionic liquids synthesized by a chemical laboratory.
文摘Polyparaphenylene(PPP) is prepared by AlCl 3-CuCl 2 catalysts with benzene as the monomer and is doped by chemical method and N + ion implantation. The influences of the concentration, temperature and time of chemical doping and the dose, energy and temperature of ion implantation, on PPP conductivity are investigated. The results showed that the conductivity of PPP can be improved 4～5 orders of magnitude by ion implantation and the conductivity of PPP can reach about 0.11 S·cm -1 by chemical doping. The comparison of stability of the material conductive behavior by using the two doping methods is presented. It shows that ion implantation is better than chemical doping in stabilizing the electric conductive behavior for the material.
基金supported by the National Natural Science Foundation of China(21975091,22122902,and 52272208)the Fundamental Research Fund for the Central Universities of China(2662023LXPY001 and 2662021JC004).
文摘Lithium plating/stripping occurs at the a node/electrolyte interface which involves the flow of electrons from the current collector and the migration of lithium ions from the solid-electrolyte interphase(SEI).The dual continuous rapid transport of interfacial electron/ion is required for homogeneous Li deposition.Herein,we propose a strategy to improve the Li metal anode performance by rationally regulating the interfacial electron density and Li ion transport through the SEI film.This key technique involves decreasing the interfacial oxygen density of biomass-derived carbon host by regulating the arrangement of the celluloses precursor fibrils.The higher specific surface area and lower interfacial oxygen density decrease the local current density and ensure the formation of thin and even SEI film,which stabilized Li^(+)transfer through the Li/electrolyte interface.Moreover,the improved graphitization and the interconnected conducting network enhance the surface electronegativity of carbon and enable uninterruptible electron conduction.The result is continuous and rapid coupled interfacial electron/ion transport at the anode/electrolyte reaction interface,which facilitates uniform Li deposition and improves Li anode performance.The Li/C anode shows a high initial Coulombic efficiency of 98%and a long-term lifespan of over 150cycles at a practical low N/P(negative-to-positive)ratio of 1.44 in full cells.
基金supported partially by the project of State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(LAPS21004)the National Natural Science Foundation of China(51972110,52102245,52072121)+5 种基金the Beijing Science and Technology Project(Z211100004621010)the Beijing Natural Science Foundation(2222076,2222077)the Huaneng Group Headquarters Science and Technology Project(HNKJ20-H88)the Hebei Natural Science Foundation(E2022502022)the Fundamental Research Funds for the Central Universities(2021MS028,2020MS023,2020MS028)the NCEPU“Double First-Class”Program。
文摘Polyethylene oxide(PEO)-based electrolytes are considered as one of the most promising solid-state electrolytes for next-generation lithium batteries with high safety and energy density;however,the drawbacks such as insufficient ion conductance,mechanical strength and electrochemical stability hinder their applications in metallic lithium batteries.To enhance their overall properties,flexible and thin composite polymer electrolyte(CPE)membranes with 3D continuous aramid nanofiber(ANF)–Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)nanoparticle hybrid frameworks are facilely prepared by filling PEO–Li TFSI in the 3D nanohybrid scaffolds via a solution infusion way.The construction of the 3D continuous nanohybrid networks can effectively inhibit the PEO crystallization,facilitate the lithium salt dissociation and meanwhile increase the fast-ion transport in the continuous LATP electrolyte phase,and thus greatly improving the ionic conductivity(~3 times that of the pristine one).With the integration of the 3D continuity and flexibility of the 3D ANF networks and the thermostability of the LATP phase,the CPE membranes also show a wider electrochemical window(~5.0 V vs.4.3 V),higher tensile strength(~4–10times that of the pristine one)and thermostability,and better lithium dendrite resistance capability.Furthermore,the CPE-based Li FePO_(4)/Li cells exhibit superior cycling stability(133 m Ah/g after 100 cycles at 0.3 C)and rate performance(100 m Ah/g at 1 C)than the pristine electrolyte-based cell(79 and 29m Ah/g,respectively).This work offers an important CPE design criteria to achieve comprehensivelyupgraded solid-state electrolytes for safe and high-energy metal battery applications.
文摘Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) (PVA) at 90 degree C and act as plasticizer in the blend films cast from the solution. Only a glass transition temperature is observed for all these blends indicating the formation of compatible blends from these polyesters with PVA. These blends exhibit manifold characteristics such as ionic conductivity, complex formation with metal ions, absorption of moisture and color changes. The electric conductivity of the copolyesters and blends is in the range of 10** minus **6 Scm** minus **1. The blends with PVA forms complexes with Cu**2** plus and Co**2** plus . The coordination structure with two chelate rings is suggested for these polymer blend/metal complexes. (Author abstract) 10 Refs.
基金the National Natural Science Foundation of China(No.52130307)Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(No.2018-K05).
文摘A series of brominated polynorbornene derivatives,including bulky steric hydrophobic groups and highly physical and chemical stable backbones,were synthesized via ring-opening metathesis polymerization and post-functionalized with trimethylammonium(QA),N-methylimidazole(Im),N-methylpyrrolidinium(Pyr)or N-methylpiperidinium(Pip)to construct the entire anion exchange membranes(AEMs).Benefited from prominent phase-separated morphology,PBO-x%-y(x=66,68,70;y=QA,Im,Pyr,Pip)AEMs with ion exchange capacity(IEC)approaching 2.0 meq·g^(−1)exhibited super high hydroxide conductivities.Thereinto,PBO-70%-Pip possessed the highest hydroxide conductivity of 137.3 mS·cm^(−1)at 80℃Moreover,all membranes exhibit low swelling ratio(SR)(the SR of PBO-66%-QA was just 8.6%at 80℃).That is,bulky steric hydrophobic groups play a crucial role in balancing the high hydroxide conductivity and low SR in AEMs.Furthermore,three AEMs(PBO-66%-QA,PBO-68%-Pyr,PBO-70%-Pip)showed good alkaline stability after immersion into 1.0 mol/L NaOH aqueous solution at 80℃for 480 h without any degradation.
文摘Green method for preparation of ion-conducting membranes(ICM) based on bacterial cellulose nanofibers(CNF) modified by a copolymer of sodium acrylate and 2-acrylamido-2-methylpropanesulfonic acid was elaborated. FTIR and NMR data confirmed grafting of polyacrylate onto cellulose surface. Formation of porous structure of the ICM was controlled by SEM and AFM. The maximal ionic conductivity of the membranes reaches 1.5 and 3.1 mS·cm^(-1)(60 ℃ and 98% relative humidity) when they are saturated with water or H_2SO_4(1 mol·L^(-1)) electrolyte,respectively. Prepared ICM was tested as a separator in a symmetrical supercapacitor with electrodes based on polyaniline hydrogel. The assembled cell demonstrate ability to operate at high current density up to 100 A·g^(-1) maintaining specific capacitance 165 F·g^(-1). Maximal specific capacitance of 289 F·g^(-1) was achieved at current density 1 A·g^(-1). Retaining of 90% of initial capacitance after 10000 of charge-discharge cycles proves high electrochemical stability of prepared ICM.
基金supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Ministry of Knowledge Economy (No. 20124030200070), Republic of Korea
文摘Herein, we developed novel silicon-carbon-nitrogen （SiCN） composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperatures of 700 ℃, 1000 ℃ and 1300 ℃, the SiCN composites prepared at 1000 ℃ showed the highest capacity with outstanding battery cycle life by cyclic voltammetry and electrochemical impedance spectroscopy. Such good battery and electrochemical performances should be attributed to a proper ratio of carbon and nitrogen or oxygen in the SiCN composites. Furthermore, our SiCN electrode possessed better lithium ion conductivity than pure silicon nanoparticles. This work demonstrates that polymer-derived composites are among the promising strategies to achieve highly stable silicon anodes for rechargeable batteries.
文摘Humidity measurement in a very low moisture atmosphere was studied by using solid electrolyte film coated with porous electrodes,considering its application to the moisture monitoring of SF_6 gas-insulated high voltage instruments such as gas-insulated switchgear (GIS) and gas circuit breakers (GCBs).Compared to the AC impedance values measured in an ambient atmosphere where the moisture atmosphere is far higher than that in these instruments,considerably large impedance values were obtained in a very low moisture atmosphere.The impedance was systematically measured in accordance with the conditions of these instruments whose moisture contents were less than 1 000×10^(-6).A good correlation was obtained between the impedance values and the moisture contents.The frequency characteristics of the impedance were analyzed based on a conventional equivalent circuit where a number of CR circuits were connected in series.Considering the dielectric relaxation of each circuit,it was found that the frequency characteristics of the impedance can be explained by the equivalent circuit. Two semicircles were clearly obtained in the Cole-Cole impedance plot which are thought to reflect the impedance characteristics of the film and the electrodes.The AC impedance can be a good indicator of the moisture content of SF_6 gas-insulated high voltage instruments.
