Selective exchange of alkali metal ions on EAB zeolite

EAB zeolite was successfully prepared and applied to selective adsorption of Li^(+),Na^(+)and K^(+)ions.The physical and chemical properties of the adsorbent were characterized by X-ray diffraction(XRD),X-ray fluorescence(XRF),scanning electron microscope(SEM)and thermogravimetry(TG)methods.The ion exchange behaviours for Li^(+),Na^(+)and K^(+)ions in monomcomponent and multicomponent solutions were studied.In independent ion exchange,the ion exchange capacities ratiosα(/Na/Li)andα(K/Li)were 3.8 and 6.2,respectively.In competitive ion exchange,the selectivitiesβ(Na/Li)andβ(K/Li)increased with the initial concentrations and reached 409 and 992 when the initial concentrations was 100 mmol/L.The thermodynamic study results showed that Gibbs free energy change(ΔGΘ)of ion exchange reaction between Li-EAB and K^(+)was-34.96 kJ/mol,indicating that ion exchange of K^(+)ions was more energetically favourable than Li^(+)ions.The calculation results showed that the energy barriers of ion exchange increased in the order K^(+)Na^(+)<Li^(+).The study shows that EAB zeolite is potential to be used in the separation of alkali ions.

Gallium-based anodes for alkali metal ion batteries

Alkali metal ion batteries(AMIBs)are playing an irreplaceable part in the energy revolution,due to their intrinsic advantages of large capacity/power density and abundance of alkali metal ions in the earth’s crust.Despite their great promise,the inborn deficiencies of commercial graphite and other anodes being researched so far call for the quest of better alternatives that exhibit all-round performance with the balance of energy/power density and cycling stability.Gallium-based materials,with impressive capacity utilization and self-healing ability,provide an anticipated solution to this conundrum.In this review,an overview on the recent progress of gallium-based anodes and their storage mechanism is presented.The current strategies used as engineering solutions to meet the scientific challenges ahead are discussed,in addition to the insightful outlook for possible future study.

Effect of alkali metal ions on the formation mechanism of HCN during pyridine pyrolysis

The catalytic effects of alkali metal ions(Na^(+)and K^(+))on NO_(x)precursor formation during coal pyrolysis were investigated using the N-containing compound pyridine as a model compound.Density functional theory calculations at the B3LYP/6-31G(d,p)level of theory were conducted to elucidate the mechanism of pyridine pyrolysis and the pathways for HCN formation.The calculation results indicate that Na^(+)and K^(+)have distinct influences on different pyrolysis reactions;these alkali metal ions facilitate the initial hydrogen transfer from C_(1)to N and C_(2),whereas they hinder the other hydrogen migration reactions.Both Na^(+)and K^(+)significantly reduce the activation energies for C–C bond breakage and triple-bond formation,whereas they increase the activation energies for the isomerization reactions.The different effects essentially result from the distinct charge distributions induced by the two ions.Due to the distinct influences on the different reactions,the rate-determining steps are modulated,affecting the competitiveness of the different possible pathways of HCN formation.The formation of HCN from pyridine is promoted in the presence of Na^(+)and K^(+)because all the overall activation energies are decreased for different pathways.The calculation results agree well with previous experimental studies.Thus,the findings offer a new and promising approach to reveal the formation mechanism of NO_(x)and facilitate the control of NO_(x)for coal utilization.

Effect of Alkali Metal Ions(Li＋, Na＋ and K＋) on the Luminescent Properties of ZnTiO3：Eu3＋ Phosphors

A series of red emitting ZnTiO3 phosphors co-doped with Eu3＋） and alkali metal ions（Li＋, Na＋ and K＋） was prepared by sol-gel method. The crystal structure of the phosphors was investigated by using X-ray diffraction（XRD） and transmission electron microscopy（TEM） after annealing at 700 ℃. The results show that the crystal structure belongs to the hexagonal phase of ZnTiO3 with space group R-3：R. The influence of site occupancy of different alkali metal ions on the emission of ZnTiO3：Eu3＋） phosphors was investigated in detail. The emission intensity was significantly enhanced by introducing alkali metal ions. In contrast to Eu3＋） singly doped ZnTiO3, the red emission intensities of ZnTiO3：Eu3＋） with 4 mol% alkali metal ions（Li＋, Na＋, K＋） were enhanced by about 2.1, 1.7 and 1.4 times, respectively. In addition, the Commission Internationale Ed I＇eclairage（CIE） chromaticity coordinates of ZnTiO3：Eu3＋）, Li＋（0.672, 0.328） are quite similar to the National Television Standard Committee（NTSC） standard values for the red（0.670, 0.380）.

First-principles study on β-GeS monolayer as high performance electrode material for alkali metal ion batteries

Based on the density functional theory calculations,we have investigated the feasibility of two-dimensionalβ-GeS monolayer as high-performance anodes for alkali metal ion batteries.The results show that the electrical conductivity of β-GeS monolayer can be enhanced after adsorbing the alkali metal atoms owing to the semiconductor-to-metal transition.The low diffusion barriers of alkali metal atoms on the β-GeS surface indicate a rapid charge/discharge rate without metal clustering.Moreover,the low average open-circuit voltage(0.211 V)and a high theoretical capacity(1024 mAh·g^(-1))for Na suggest that theβ-GeS monolayer is a promising anode material for Na-ion batteries with high performance.

Revealing the structure design of alloyed based electrodes for alkali metal ion batteries with in situ TEM

Alloyed based anode materials with high theoretical specific capacity and low reaction potential are considered to be highly potential high-energy density anode materials for alkali metal ion batteries(AMIBs).Thus,the design of alloyed based materials with high electrochemical performance has attracted great attention.Among the numerous characterization methods for guiding electrode materials design,in situ transmission electron microscopy(TEM)gradually plays an irreplaceable role due to its high temporal and spatial resolution in directly observing the change of morphology,crystal structure and element evolutions.Herein,we reviewed the two current research hotspots and mainly focused on the structure design of alloyed based electrode material under the guidance of in situ TEM.Specifically,various nanostructure designs of alloyed based electrode materials with guidance of in situ TEM were employed to solve the key scientific issues of the violent volume change during alloying/dealloying processes for enhanced electrochemical performances.Mainly through introducing buffer space in the electrode material to reduce volume change to improve structural stability,including porous structure(0 D),nanotube structure(1 D),simple hollow structure,yolk-shell structure and some hybrid hollow structures(3 D).Furthermore,the direct guidance of in situ TEM is expected for creating new opportunities to nextgeneration electrode material design for AMIBs.

Effect of Doped Alkali Metal Ions on the SO_(2) Capture Performance of MnO_(2) Desulfurization Materials at Low Temperature

Sulfur dioxide(SO_(2))emissions from diesel exhaust pose a serious threat to the environment and human health.Thus,desulfurization technology and the performance of desulfurization materials must be improved.In this study,MnO_(2) was modified with various alkali metal ions using the impregnation method to enhance its SO_(2) capture performance.The composites were characterized intensively by scanning electron microscopy,energydispersive X-ray spectroscopy,X-ray diffraction spectroscopy,and Brunauer-Emmett-Teller theory.The SO_(2) capture performance of these composites were measured via thermogravimetry,and the effect of doping with alkali metal ions on the SO_(2) capture performance of MnO_(2) was investigated.Results showed that the SO_(2) capture performance of MnO_(2) could be enhanced by doping with alkali metal ions,and the MnO_(2) composite doped with LiOH(2.0 mol/L)had the best SO_(2) capture capacity(124 mgSO_(2)/gMaterial),which was 18%higher than that of pure MnO_(2).Moreover,the type and concentration of alkali metal ions had varying effects on the SO_(2) capture performance of MnO_(2).In our experiment,the SO_(2) capture performance of the MnO_(2) doped with NaOH,LiCl,Na2CO3,K2CO3,and Li2CO3 composites were worse than that of pure MnO_(2).Therefore,the influences of the type and concentration of alkali metal ions to be doped into desulfurization materials must be considered comprehensively.

Luminescence properties of alkali metal ions sensitized Ca FCl:Tb^(3+) nanophosphors

A series of CaFCl：Tb3＋ and CaFCI：Tb3＋,A＋ （A=Li, Na and K） nanophosphors were synthesized by the one-step sol-gel method, which were reported for the first time. The sample consisted of monodisperse particles, the average size of which was 37 nm. The emissions of Tb3＋ ions and oxygen defects OF＇ were demonstrated in the CaFCl：Tb3＋ samples. The former was made up of several peaks at 488, 545, 587 and 623 nm, ascribed to 5D4→7FJ （j=6-3） transitions of Tb3＋ ions. The latter was shown as a broad band peaked at about 450 nm. Alkali metal ions A＋ （A=Li, Na and K） were introduced as the charge compensators to improve the luminescence of samples. The influence of charge compensators on the emissions of Tb3＋ ions and oxygen defects OF＇ was investigated by the measurement of fluorescence spectra and luminescence decay curves. The results indicated that all the charge compensators weakened the defects emission. Furthermore, Li＋ ion was the best charge compensator, because it not only reduced the defects emission but also increased the emission intensity of Tb3＋ significantly. Our results suggested that this nanophosphor sensitized by the charge compensator might broaden potential applications of rare-earth doped CaFCl.

Rational construction of hollow nanoboxes for long cycle life alkali metal ion batteries

Hollow nanostructures are extremely attractive in energy storage and show broad application prospects.But the preparation method is accompanied by a complicated process.In this article,the CoZn-based hol-low nanoboxes with electrochemical synergy are prepared in a simple way.This structure can effectively shorten the transmission distance of ions and electrons,and alleviate the volume expansion during the cycle.In particular,bimetallic oxides are rich in oxygen vacancies,providing more active sites for electro-chemical reactions.In addition,the stepwise oxidation-reduction reaction can also improve the volume change of the electrode material.According to the kinetic analysis and density functional theory(DFT)calculation,it is confirmed that the synergistic effect of the bimetallic oxide can accelerate the reaction kinetics.Based on these characteristics,the electrode exhibits stable cycle performance and long cycle life in alkali metal ion batteries,and can provide reversible capacities of 302.1(LIBs,2000 cycles),172.5(SIBs,10000 cycles)and 109.6(PIBs,5000 cycles)mA h g^(-1)at a current density of 1.0 A g^(-1),respectively.In ad-dition,by assembling(LiCoO_(2)//CoZn-O_(2))and(Na_(3)V_(2)(PO_(4))_(3)//CoZn-O_(2))full-cells,the practical application value is demonstrated.The sharing of this work introduces a simple way to synthesize hollow nanoboxes,and shows excellent electrochemical performance,which can also be expanded in other areas.

Influence of alkali metal ions on thermal stability of Bi-activated NIR-emitting alkali-aluminoborosilicate glasses

We study the influence of alkali oxides on the near-infrared（NIR）-emitting thermal stability of Bi-doped R2O–Si O2–B2O3–Al2O3（R = Li, Na, K） glasses below Tg. Results show that undergoing heat treatment, remarkable luminescence quenching occurs for the glasses containing Na2 O and K2 O due to the formation of Bi metallic colloids, whereas the glass with Li2 O shows much better thermal stability. These changes can be understood by the tendency of modifier cations with lower mobility and higher tightness network to restrain the transport of Bi-related NIR-emitting centers. The results provide a scientific reference for composition design of Bi-doped optical fiber.

Two-dimensional organic cathode materials for alkali-metal-ion batteries

With the increasing demand for large-scale battery systems in electric vehicles（EVs） and smart renewable energy grids, organic materials including small molecules and polymers utilized as electrodes in rechargeable batteries have received increasing attraction. In recent years, two-dimensional（2D） organic materials possessing planar layered architecture exhibit optional chemical modification, high specific surface area as well as unique electrical/magnetic properties, which have been emerging as the promising functional materials for wide applications in optoelectronics, catalysis, sensing, etc. Integrating with high-density redox-active sites and hierarchical porous structure, significant achievements in 2D organic materials as cathode materials for alkali-metal-ion batteries have been witnessed. In this review, the recent progress in synthetic approaches, structure analyses, electrochemical characterizations of 2D organic materials as well as their application in alkali-metal-ion batteries containing lithium ion battery（LIB）, lithium sulfur battery（LSB）, lithium air battery（LAB） and sodium ion battery（SIB） are summarized systematically,and their current challenges including cycling stability and electron conductivity for cathode materials in battery fields are also discussed.

Understanding charge transfer of Li^+ and Na^+ ions scattered from metal surfaces with high work function

For Li^＋ and Na^＋ ions scattered from high work function metal surfaces, efficient neutralization is observed, and it cannot be explained by the conventional free electron model. In order to explain these experimental data, we investigate the velocity-dependent neutral fraction with the modified Brako–Newns（BN） model. The calculated results are in agreement with the experimental data. We find that the parallel velocity effect plays an important role in neutralizing the Li^＋ and Na^＋ ions for large angle scattering. The nonmonotonic velocity behavior of neutral fraction is strongly related to the distance-dependent coupling strength between the atomic level and metal states.

燃煤锅炉烟气湿法脱硫废水中重金属及钙镁离子沉淀规律研究

燃煤锅炉烟气湿法脱硫废水中的重金属及钙镁等离子危害较大,开展其沉淀去除规律的研究有利于废水中有用元素的资源化回收和废水的回用。采用碱液沉淀法对脱硫废水进行分级处理,对沉淀产物采用SEM-EDS等手段进行表征。结果表明,采用氢氧化钙作为沉淀剂可以实现去除重金属、回收镁资源及去除氟化物和降低废水硬度等多种目标。在去除重金属离子的过程中,当脱硫废水pH值为9.0~9.5时,废水中的重金属离子可得到有效去除且达到污水排放标准,镁离子几乎没有损失,钙增加率也较低,仅为4.6%以下;将废水pH值调整为9.5~9.7可有效回收废水中的镁元素,镁的回收率在62%以上,回收效果较好。在碱性条件下,向废水中投加Na_(2)CO_(3)可有效降低废水中的钙离子和残留的镁离子,实现废水降硬的目标。不同pH值下沉淀物的SEM-EDS能谱显示,对脱硫废水进行梯级pH处理可以达到分级去除重金属污染物和回收镁元素的目标。通过对脱硫废水中重金属及钙镁结垢离子的沉淀规律研究,实现了废水的分质分盐有用成分的资源化回用,避免了产生杂盐危废造成二次污染的可能,达到了脱硫废水的零排放的目标。

有机膦酸盐对碱矿渣胶凝材料铅离子固化性能的提升作用

有机膦酸盐是一种极强的金属螯合剂,在溶液环境中可有效固化重金属离子。然而,目前关于有机膦酸盐改性水泥基材料重金属离子固化性能的研究较少。本工作研究了羟基乙叉二膦酸四钠(HEDP-4Na)和温、湿度交替变化的养护环境对碱矿渣胶凝材料(Alkali-activated slag-based materials,AASM)铅离子固化性能的影响,并分析了其物相组成、孔隙结构和微观形貌。结果显示:HEDP-4Na显著提升了AASM的铅离子固化性能,当其掺量为0.3%时,标准养护至28 d的AASM铅离子浸出浓度相比未掺入HEDP-4Na的对照组降低了34.6%,这与HEDP-4Na促进了AASM低钙硅比水化产物的生成,提升了水化产物吸附、封裹铅离子并形成C-Pb-S-H的能力,改善了其微观孔隙结构有关;温、湿度交替变化养护环境下,AASM的劣化加速,导致其铅离子固化性能下降,但掺HEDP-4Na的AASM铅离子浸出浓度仍显著低于未掺入HEDP-4Na的对照组。温、湿度交替变化养护时铅离子固化性能下降主要与AASM水化产物的生成受抑制,以及基体孔隙率的提高有关。

Effect of alkali metal oxides R_2O (R=Na,K) on 1.53 μm luminescence of Er^(3+)-doped Ga_2O_3-GeO_2 glasses for optical amplification

This paper reported the thermal stability and spectroscopic properties of Ga2O3-GeO2-Na2O-K2O （GGNK） glasses doped with Er3＋. The GGNK glasses were characterized by differential scanning calorimetry （DSC）, Raman spectra, absorption and infra- red-visible fluorescence spectra. Measured DSC result showed that these glasses possessed an excellent stability （AT=188.6 ℃）. The relationship between glass composition and Judd-Ofelt intensity parameters and other optical properties of Er3＋, such as the absorption and stimulated emission cross-sections, were clarified. Meanwhile an intense broadband 1.53μm emission with a full width at half- maximum of 51 nm and peak emission cross-section of 9.32×10^-21 cm2 of Er3＋-doped GGNK glass was obtained upon 980 nm di- ode-laser excitation. Effects of K2O replacing Na2O on the thermal stability and spectroscopic properties were investigated. It was found that the incorporation of K2O into Er3＋-doped Ga2O3-GeO2-Na2O glass could effectively improve the 1.53 μm emission luminescence. The results showed that GGNK glass might be more attractive host material for their application in C-band optical fiber amplifiers.

低温水系碱金属离子电池的研究进展

水系碱金属离子电池因具有高安全性、低成本和环境友好等优势而成为前沿研究的热点之一,在大规模储能领域具有良好的应用前景.然而,许多水系碱金属离子电池在低温条件下出现运行故障或展现出极低的放电比容量,严重限制了其在恶劣的严寒气候条件下的广泛应用.本综述首先梳理了近年来低温水系碱金属离子电池的研究进展.随后从电解液、电极和界面三个方面分别探讨了水系碱金属离子电池在低温下运行所面对的挑战和相应的失效机制,同时系统地介绍了提高电池低温性能的改性策略并加以评述,以期为水系碱金属离子电池低温性能的进一步提升及其实际应用提供参考并指明方向.

量子点/碳复合材料在碱金属离子电池的应用进展

碱金属离子电池作为可充电电池,是目前重要的储能设备之一。它凭借能量密度大、工作电压高、无“记忆效应”、自放电小、绿色无污染等优点在近些年来受到人们的广泛关注。电极材料是影响碱金属离子电池电化学性能的重要因素之一,因此,寻求比容量高、结构稳定的电极材料是推动碱金属离子电池发展的关键。量子点/碳复合材料(QDs/C)集合量子点与碳材料的优势,是碱金属离子电池优异的候选电极材料。本文首先对量子点进行简要介绍,然后分别综述单质量子点/碳复合材料、化合物量子点/碳复合材料及异质结构量子点/碳复合材料在碱金属离子电池中的应用进展。最后,分析量子点/碳复合材料作为碱金属离子电池电极材料的优势与不足,针对目前存在的问题提出了未来发展的方向:(1)探索新型方法,解决量子点及其复合材料的团聚问题;(2)研究SEI膜的结构性能等,解决首次库仑效率偏低的问题;(3)明确反应机理,获取更优异的电化学性能。

镧系离子掺杂Li_(0.9)K_(0.1)NbO_(3)荧光粉的多色多模荧光调控及防伪应用

多色多模荧光材料在信息安全加密领域具有重要的应用价值,然而目前多色多模荧光材料的设计合成仍然是一个挑战.本文采用高温固相法制备了一系列Li_(1–x)K_(x)NbO_(3):Pr^(3+)/Er^(3+)/Tm^(3+)单掺及双掺荧光粉.通过X射线衍射仪、扫描电子显微镜、荧光光谱仪以及自搭建的加热装置,对其结构、形貌、光谱学特性以及热释光性能进行表征.研究了Li_(0.9)K_(0.1)NbO_(3)基质中Pr^(3+),Er^(3+),Tm^(3+)单掺及共掺调控的多色多模荧光特性与上/下转换、余辉和光激励荧光机理.基于优异的光谱特性,将三基色荧光粉设计成蝴蝶图案,采用不同波长光选择激发,展现了图案和色彩的动态变化,具有高阶多色多模防伪能力.

沸石中碱金属阳离子对CO_(2)/N_(2)O吸附分离性能的影响

氧化亚氮(N_(2)O)是仅次于CO_(2)和CH_(4)的第三大温室气体,排放后加剧温室效应,而N_(2)O具有广泛的用途,因此对其进行回收具有重要意义。苯酚法和环己烷法生产己二酸时排放的尾气中CO_(2)与N_(2)O共存,二者具有相同的动力学直径和相似的物理性质,它们的分离具有很大的挑战。研究了A型沸石中一价碱金属阳离子(Li^(+)、Na^(+)、K^(+)、Cs^(+))对CO_(2)/N_(2)O吸附分离性能的影响,通过XRD、ICP-OES、SEM和TGA进行表征,并对吸附性能、IAST选择性以及分离性能进行了研究。研究结果表明,随着碱金属阳离子半径的增大,CO_(2)和N_(2)O的吸附容量逐渐降低,CsA几乎对CO_(2)和N_(2)O均不吸附;但CO_(2)/N_(2)O选择性却呈相反的趋势,其中KA的选择性达到最高(2.6),混合气体(VCO_(2)/VN_(2)O=50%/50%)穿透实验结果也表明KA具有一定的CO_(2)/N_(2)O吸附分离性能。

高电压/宽温域水系碱金属离子电池的研究进展

水系储能器件具有固有的高安全性、环境友好性和成本低的优势,在未来智能电网、便携式/可穿戴电子产品等领域显示出巨大的应用潜力。然而水的热力学分解电压低、冰点高,导致水系电解液电化学稳定电压窗口窄以及凝固点高,极大地限制了水系储能器件的能量密度与宽温域应用。因此,设计耐高电压、抗冻的水系电解液,成为水系储能器件大规模、多场景应用的关键。本文系统综述了高电压/宽温域水系碱金属离子电池电解液设计的研究进展,从热力学和动力学角度出发,分别重点介绍提高电解液电压窗口和工作温度范围的各类策略以及相关作用机制。进一步提出宽温域、高压水系电解液的潜在设计思路,并对高性能水系碱金属离子电池的发展方向进行展望。