Structural Engineering of Anode Materials for Low-Temperature Lithium-Ion Batteries:Mechanisms,Strategies,and Prospects

The severe degradation of electrochemical performance for lithium-ion batteries(LIBs)at low temperatures poses a significant challenge to their practical applications.Consequently,extensive efforts have been contributed to explore novel anode materials with high electronic conductivity and rapid Li^(+)diffusion kinetics for achieving favorable low-temperature performance of LIBs.Herein,we try to review the recent reports on the synthesis and characterizations of low-temperature anode materials.First,we summarize the underlying mechanisms responsible for the performance degradation of anode materials at subzero temperatures.Second,detailed discussions concerning the key pathways(boosting electronic conductivity,enhancing Li^(+)diffusion kinetics,and inhibiting lithium dendrite)for improving the low-temperature performance of anode materials are presented.Third,several commonly used low-temperature anode materials are briefly introduced.Fourth,recent progress in the engineering of these low-temperature anode materials is summarized in terms of structural design,morphology control,surface&interface modifications,and multiphase materials.Finally,the challenges that remain to be solved in the field of low-temperature anode materials are discussed.This review was organized to offer valuable insights and guidance for next-generation LIBs with excellent low-temperature electrochemical performance.

Modification of FGD gypsum in hydrothermal mixed salt solution

A novel utilization way of the sludge from wet calcium-based flue gas desulfurization （FGD） processes has been developed in this paper. This study focused on the conversion of the FGD gypsum into α-hemihydrate calcium sulfate by a hydrothermal salt solution method at atmospheric pressure. Experimental study has been carried out in a batch reactor. Qualitative and quantitative analyses were made by DSC/TG thermal analysis, SEM, XRD, metalloscope and chemical analysis. The experimental results showed that the modification of FGD gypsum was controlled by the dissolution and recrystallization mechanisms. With the introduction of FGD gypsum the salt solution was supersaturated, then crystal nucleus of α-hemihydrate calcium sulfate were produced in the solution. With the submicroscopic structure of FGD gypsum crystal changed, the crystal nucleus grew up into α-hemihydrate calcium sulfate crystals. Thus ,the modification of FGD gypsum was fulfilled.

Influence of chromium modification on the properties of MnO_x-FeO_x catalysts for the low-temperature selective catalytic reduction of NO by NH_3

Catalytic properties of MnOx-FeOx complex oxide （hereafter denoted as Mn-Fe） catalysts modified with different loadings of chromium oxide were investigated by using the combination of physico-cbemical techniques, such as N2 physisorption, X-ray diffraction （XRD）, high-resolution transmission electron microscope （HRTEM）, in situ Fourier transform infrared spectroscopy （in situ FT-IR） and temperature-programmed reduction （TPR） and their catalytic activities were evaluated with the selective catalytic reduction （SCR） of NOx by NH3. It was found that with the addition of Cr, more NO could be removed in the low-temperature window （below 120 ℃）. Among the tested catalysts, Mn-Fe- Cr （2 ： 2 ： 1） catalyst exhibited the best catalytic performance at 80 ℃ with the NO conversion higher than 90%. The combination of the reaction and characterization results indicated that （1） the strong interaction among tertiary metal oxides existed in the catalysts when Cr was appropriately added, which made the active components better dispersed with less agglomeration and sintering and the largest BET specific surface area could be obtained; （2） Cr improved the low-temperature reducibility of the catalyst and promoted the formation of the active intermediate （-NH3＋）, which favored the low-temperature SCR reaction.

Enhancing hydrothermal stability of nano-sized HZSM-5 zeolite by phosphorus modification for olefin catalytic cracking of full-range FCC gasoline

In this study, phosphorus modification by trimethyl phosphate impregnation was employed to enhance the hydrothermal stability of nano‐sized HZSM‐5 zeolites. A parallel modification was studied by ammonium dihydrogen phosphate impregnation. The modified zeolites were subjected to steam treatment at 800 °C for 4 h (100% steam) and employed as catalysts for olefin catalyticcracking (OCC) of full‐range fluid catalytic cracking (FCC) gasoline. X‐ray diffraction, N2 physicaladsorption and NH3 temperature‐programmed desorption analysis indicated that, although significantimprovements to the hydrothermal stability of nano‐sized HZSM‐5 zeolites can be observedwhen adopting both phosphorus modification strategies, impregnation with trimethyl phosphatedisplays further enhancement of the hydrothermal stability. This is because higher structural crystallinityis retained, larger specific surface areas/micropore volumes form, and there are greaternumbers of surface acid sites. Reaction experiments conducted using a fixed‐bed micro‐reactor(catalyst/oil ratio = 4, time on stream = 4 s) showed OCC of full‐range FCC gasoline-under a fluidized‐bed reaction mode configuration-to be a viable solution for the olefin problem of FCC gasoline.This reaction significantly decreased the olefin content in the full‐range FCC gasoline feed, andspecifically heavy‐end olefins, by converting the olefins into value‐added C2–C4 olefins and aromatics.At the same time, sulfide content of the gasoline decreased via a non‐hydrodesulfurization process.Nano‐sized HZSM‐5 zeolites modified with trimethyl phosphate exhibited enhanced catalytic performance for OCC of full‐range FCC gasoline.

Influences of Low-Temperature Hydrothermal Fluids on the Re-distributions and Occurrences of Associated Elements in Coal——A Case Study from the Late Permian Coals in the Zhijin Coalfield, Guizhou Province. Southern China

The occurrences of associated elements and their genetic factors in the No. 30 coal seam in the Zhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma-atomic emission spectroscopy, and a scanning electron microscope equipped with an energy-dispersive X-ray analyzer. And, a microscope photometer system (Leitz MPV-Ⅲ) was used to observe the characteristics of coal petrology. According to the influence degree by the siliceous low-temperature hydrothermal fluids, the organic matter is divided into four types: A, B, C, and D of the hydrothermally-altered organic matter (HAOM). The study shows that the high content of Fe (2.31%) is not from pyrite, but mostly from the siliceous low-temperature hydrothermal fluids. The occurrences of the associated elements in the four organic matter types are different. The contents of Fe, Si, and Al are decreasing, but S and Cu are increasing in the order of the HAOM-A, HAOM-B, HAOM-C, and HAOM-D. The losing rate of sulfur in organic matter is 0.35% and the content of Fe taken from the low-temperature hydrothermal fluids into the organic matter is 0.794% during the siliceous low-temperature hydrothermal fluids invading the coal seam. The above facts indicate that the low-temperature hydrothermal fluids play a crucial role in the re-distributions and occurrences of associated elements in coal.

Characterization of Pr-CeO_2 Nano-crystallites Prepared by Low-temperature Combustion&Hydrothermal Synthesis

Pr-CeO2 Nano-crystalline red pigments were prepared by low-temperature combustion with a later hydrothermal treatment using Ce（NO3）3·6H2O and Pr6O11 as raw materials. The phase composition, coloring mechanism and morphology of pigments were analyzed by XRD, SEM, EDS and XPS. Results showed that Pr-CeO2 solid solution with a fluorite structure was obtained by the diffusion of Pr^＋3 into CeO2 crystal lattice during the synthesis process. XPS analysis indicated that Pr^＋3 substitutes Ce^＋4 in CeO2 and is compensated by oxygen vacancies. Compared with low-temperature combustion synthesis, the Pr-CeO2 pigments prepared with a subsequent hydrothermal treatment have an average grain size of about 16.70 nm, and the crystallinity and red tonality are improved.

Morphological modifications of C60 crystal rods under hydrothermal conditions

We observed morphological modification of rod-shaped C60 solvate crystals using a facile hydrothermal method.The initial C60 rods were changed from smooth rods to rough rods,porous rods or pieces under different hydrothermal conditions.During the hydrothermal treatment,the initial samples underwent a decomposition-recrystallization process,which can be tuned by the content of alcohol in the hydrothermal solution,thereby leading to modification of the morphological properties of the initial C60 rods.In addition,the rough and porous C60 rods prepared in our work exhibit excellent photoluminescence intensities that are approximately 7 and 3 times higher than those of pure C60 powders,respectively.Our results suggest that the hydrothermal method is a potential route for fabricating fullerene materials with controllable morphologies and novel functions.

One-step post-synthesis treatment for preparing hydrothermally stable hierarchically porous ZSM-5

Hierarchically porous ZSM‐5 (SiO2/Al2O3 ≈ 120) containing phosphorus was prepared by a one‐step post‐synthesis treatment involving controlled desilication and phosphorous modification. The hierarchically porous ZSM‐5 featured high thermal and hydrothermal stability. The obtained ZSM‐5zeolites were systematically characterized by X‐ray diffraction, scanning electron microscopy,transmission electron microscopy, N2 adsorption‐desorption, NH3 temperature‐programmed desorption,and 27Al and 31P magic‐angle spinning nuclear magnetic resonance spectroscopy. Theprepared ZSM‐5 displayed enhanced activity and prolonged lifetime toward hydrocarbon cracking.The high activity was attributed to improved coke tolerance owing to the presence of the highlystable mesoporous network of ZSM‐5 and acid sites introduced upon phosphorus modification.Additionally a mechanism of the stabilization of the zeolites by phosphorus was proposed and discussed.

Isolation, Modification and Characterization of Finger Millet （Eleucine coracana） Starch

Isolated finger millet （Eleucine coracana） starch was subjected to different modifications （hydrothermal, acidic and enzymatic） and characterized in terms of yield, moisture, protein, ash, bulk density, swelling power, solubility, sediment volume, colour, gel consistency, water binding capacity （WBC）, pasting properties, freeze thaw stability and paste clarity, and compared with native starch. Moisture content ranged from 4%-5%. Protein and ash content were lowest in case of acid modified starch （AMS）. Hydrothermally modified starches （HTMS） showed maximum water binding, peak viscosity and syneresis. Swelling power was decreased for all modifications. Solubility and color （a and b values） decreased for AMS and EMS. However, L values increased with all modifications. EMS showed maximum bulk density, swelling power, solubility, and sediment volume and gel consistency. Paste clarity decreased with storage period and found maximum for EMS.

胺基改性壳聚糖吸附材料的制备及其对铀的吸附性能研究

研究了采用水热法制备壳聚糖微球(HTCC),再通过环氧化-胺化改性法制备胺基改性壳聚糖吸附材料(AHTCC)并用于吸附废水中的低浓度铀。利用红外光谱仪、元素分析仪、热重分析仪等对AHTCC的结构、组分和热稳定性进行表征,并考察了AHTCC对铀的吸附、解吸性能。结果表明:在pH=5~8条件下,AHTCC对溶液中铀的吸附效果较好;铀吸附平衡质量浓度为120 mg/L左右时,吸附量达最大,为151.6 mg/g;铀吸附速率在反应最初60 min较快,180 min时达到吸附平衡;以80 g/L Na_(2)CO_(3)+20 g/L NaHCO_(3)作解吸剂,铀解吸率为97.5%;对于含杂离子浓度较高的实际含铀废水,经AHTCC单次吸附,铀的去除率可达95.6%。

水热炭在吸附有机/无机污染物中的应用研究进展

水热炭材料作为一种新型碳材料,具有含氧官能团丰富、堆积密度高、热稳定性强和导电导热性优良等特点,在催化和吸附、储能材料领域具有潜在的应用价值,尤其适用于吸附各种污染物。首先介绍了水热炭的分类和制备,根据尺寸可以分为水热炭量子点和水热微球。其次综述了水热炭的酸洗改性、碱洗改性、官能团化改性以及对污染物的吸附性能和机理。改性水热炭对污染物吸附的机理包括物理吸附和化学吸附,其中物理吸附主要由范德华力所引起的分子间作用,化学吸附主要包括络合配位、离子交换、静电吸引、氧化还原反应等;最后针对水热炭现存问题进行讨论与展望,以期为改性水热炭吸附去除污染物的广泛应用提供理论支撑。

气相法磷改性对USY沸石酸性及其水热稳定性的调控

磷(P)改性是提高沸石催化剂稳定性的有效方法之一.我们考察了三氯化磷(PCl_(3))气相法和磷酸氢二铵浸渍法制备得到的不同P改性USY样品.研究发现,2种P改性方法制备的样品中P物种均能够与USY中的Si―OH发生相互作用,同时夺取附近的非骨架Al物种,将表现为L酸的Si―O(EFAl)―Al转变成显示强B酸的Si―OH―Al.非骨架Al的迁移改善了沸石的孔径分布.在600℃水热老化后发现,气相法PCl_(3)改性后样品的桥羟基没有被破坏,其原因是PCl_(3)改性后样品的P物种主要为低聚态P物种,能够更好地与附近的四配位骨架Al发生相互作用,从而保护沸石的桥羟基不被破坏.而浸渍法磷酸氢二铵改性后样品主要生成高聚态P物种,与附近的四配位骨架Al发生相互作用能力弱,保护沸石桥羟基的作用不强.因此,气相法PCl_(3)改性样品在600℃水热老化4 h后的强B酸酸量(41μmol·g^(-1))明显高于浸渍法P改性样品(21μmol·g^(-1)).在800和900℃水热老化4 h后,PCl_(3)改性样品较浸渍法P改性样品和未改性样品展现了更高的结晶保留度,结合正辛烷催化裂化反应数据,表明气相法PCl_(3)改性后的USY样品具有更高的催化活性稳定性和结构稳定性.

混维凹凸棒石对矿区土壤重金属的钝化修复

该文在引入外源Si^(2+)、Ca^(2+)和Mg^(2+)条件下,将混维凹凸棒石水热改性为新型凹凸棒石钝化材料(PSMC),用扫描电镜、X射线衍射和傅立叶红外光谱对其进行了表征,通过钝化试验探究了其对矿区土壤中重金属的钝化效果。结果表明,水热处理能使凹凸棒石及其伴生矿物转变为具有晶体结构缺陷的无定形或低结晶硅酸盐。土壤中Cd、Pb、Cu和Zn的二乙烯三胺五乙酸提取态含量在所有PSMC添加处理下均显著降低,且均在5%(w/w)的添加处理下达到最小;添加PSMC促使酸溶态的Cd、Pb、Cu和Zn向更加稳定的残渣态转化;5%的PSMC添加处理下,Cd、Pb、Cu和Zn的钝化效率分别为91.15%、84.70%、90.51%和90.09%。根据土壤管控标准风险等级,重金属的总体污染潜在风险指数随着PSMC添加量的增加而减小,Pb、Cu和Zn的环境风险指数均小于1%,Cd的的环境风险指数均小于3%(低风险)。水热改性能提高混维凹凸棒石对矿区土壤中重金属的钝化能力,进而为甘肃混维ATP黏土高值化利用提供新思路、新方法。

Fe原位改性小晶粒Silicalite-1分子筛催化醛氨缩合性能研究

吡啶及其衍生物统称为吡啶碱,其广泛应用于农药、医药等领域。Chichibabin醛氨缩合反应是目前工业制取吡啶碱最广泛的路线。目前,使用最广泛的ZSM-5分子筛受制于硅铝骨架结构的不稳定性,高活性反应周期较短(5 h),针对这一问题,本研究选用热稳定性、水热稳定性优异的Silicalite-1分子筛,使用聚乙烯吡咯烷酮(PVP)作为胶体分散剂,在水热合成分子筛的过程中向骨架中引入Fe,结合XRD、SEM、TG、BET、NH3-TPD、Py-FTIR等表征方法探究了晶化条件对Silicalite-1分子筛结晶度、孔结构和酸性质的影响。实验结果表明,在晶种投入量15%、PVP添加量3.75%时产品相对结晶度达到最高(103%),粒径约为200 nm。改性后的Silicalite-1具有更丰富的酸位点,醛氨缩合反应的初始活性由66%增加至85%,在反应进行15 h后,原料转化率和吡啶碱收率分别保持在66%和40%以上。研究提出的原位改性Silicalite-1分子筛策略极大扩宽了纯硅沸石在酸催化领域的应用,具有显著的科研价值和工业化潜力。

低阶煤和生物质水热碳化特性及水热炭功能化改性研究进展

低阶煤中大量含氧官能团赋予其强亲水性,导致孔隙表面吸收大量水分,从而增加运输成本,能源转化效率降低,因此低阶煤的清洁低碳高效转化备受关注。水热碳化反应能耗较低,可直接处理高含水率有机固体物质,是一种绿色低碳高效经济的低阶煤提质技术;而生物质作为可代替化石燃料的可再生能源,水热碳化也可大幅提高其利用率。低阶煤与生物质共水热碳化时,二者会产生一定的协同效应,相较于单一水热碳化具有更高的产率和碳保留率。对水热炭进行功能化改性,可以进一步丰富其孔隙结构,增加材料表面的官能团,进而制备出性能优异的功能性炭材料,用于CO_(2)和SO_(2)等气体吸附。综述了低阶煤和生物质单独水热碳化及共水热碳化特性,分析生物质水热碳化主要影响因素;同时对水热炭活化改性和掺杂改性方法进行了总结,比较了氮、硫掺杂及硫氮共掺杂方式、掺杂机制及改性水热炭应用范围。此外,还对改性水热炭对CO_(2)和SO_(2)吸附性能等进行了综述,探讨了多孔炭表面吸附CO_(2)和SO_(2)的机理;最后对低阶煤和生物质共水热碳化以及水热炭低成本制备气体吸附剂等未来发展方向进行了展望。

两亲型碳量子点的制备及驱油性能评价

以葡萄糖作为碳源,十二烷基羟丙基磺基甜菜碱(DHSB)作为表面修饰剂,通过一步水热法快速合成了稳定的两亲型碳量子点驱油剂(CQDs-S)。采用FTIR、TEM和DLS表征CQDs-S的结构、形貌及分散稳定性,通过界面性能测试、接触角测量、静态洗油实验研究CQDs-S的性能优势,与碳量子点驱油剂CQDs和表面活性剂DHSB对比采收率差异,分析CQDs-S提高采收率的机理。结果表明,CQDs-S是平均粒径为7.8 nm的球状颗粒,其表面修饰烷基而具有两亲性,具有良好的稳定性。质量浓度为0.1%的CQDs-S使油水界面张力降低到0.96 mN/m,使接触角减小到48.5°,静态洗油效率高达86.8%,在渗透率为50×10^(-3)μm^(2)的岩心中使采收率提高16.74%,较CQDs和DHSB有明显提升。CQDs-S能够降低油水界面张力,改变岩石润湿性,实现调堵作用,是一种高效的纳米驱油剂。

HZSM-5 的低温水热改性及其己烯芳构化性能

对HZSM-5在70,100和150℃下进行低温水热改性,分别制得催化剂T 70-HZ-5,T 100-HZ-5和T 150-HZ-5,利用X射线衍射仪、X射线荧光光谱仪、物理吸附仪、化学吸附分析仪和红外光谱仪等对上述催化剂进行表征,并对其己烯芳构化催化性能进行了评价。结果表明:低温水热改性保持了HZSM-5的完整晶相结构,提高了其硅铝比[n(Si)/n(Al)],B酸和L酸酸量比(B/L)及平均孔径;酸量的降低和孔径的增大有利于HZSM-5寿命的延长,B/L值的增大有利于选择性的提高;在反应温度405℃,反应压力0.2 MPa,质量空速2 h-1的条件下,T 100-HZ-5的催化寿命可达44 h,比改性前延长了36 h;当反应8 h时,HZSM-5的苯、甲苯和二甲苯混合物(BTX)选择性已迅速降到35%左右,而T 100-HZ-5的仍接近55%。

水热处理等物理改性方法对稻米淀粉组成及血糖生成指数的影响

本文介绍了稻米淀粉的分类和存在形态,综述了常用物理改性方法——水热处理(包括湿热处理、退火和蒸制等)改变稻米淀粉结构和成分,以及影响稻米淀粉血糖生成指数(GI)的机制。分析了影响水热处理及后续回生过程效果的因素(原料淀粉组成、温度、时间、含水量、处理次数等),并讨论了高静压、超声和微波等新型非加热淀粉物理改性方法改变稻米淀粉GI的技术特点。文章最后指出,采用加压蒸煮、高静压、超声及微波复合处理准确控制淀粉迁移、重组、糊化和回生过程,可能是未来采用物理改性方法生产低GI食物的趋势。

K_(2)CO_(3)活化低阶煤和污泥共水热炭制备多孔炭及其对CO_(2)和SO_(2)吸附性能

我国低阶煤储量大,低阶煤材料化利用是当前国家重大需求。另外,我国城市污泥排放量逐年增加,高含水率污泥资源化利用至关重要。低阶煤和污泥水热碳化可有效资源化利用原料内的硫氮元素,制备硫氮掺杂水热炭。水热炭孔隙较不丰富,对其进行活化造孔可丰富其孔隙结构,制备得到硫氮掺杂多孔炭。选用较为温和K_(2)CO_(3)作为活化剂,探究K_(2)CO_(3)活化不同次烟煤与污泥水热炭制备多孔炭材料的性质,并研究多孔炭对CO_(2)和SO_(2)的吸附性能。结果表明,次烟煤和污泥水热炭经K_(2)CO_(3)活化改性后,硫氮元素含量相较于原来的水热炭均有所减少,多孔炭的比表面积由原水热炭的23.92m^(2)/g增至331.77m^(2)/g,孔体积由原水热炭的0.07cm^(3)/g增至0.23cm^(3)/g。制备的多孔炭对CO_(2)和SO_(2)具有一定的吸附效果,次烟煤与污泥质量比为7∶3,水热碳化温度为160℃时,经700℃K_(2)CO_(3)活化所制备的多孔炭在25℃下,对CO_(2)吸附量为1.56 mmol/g;次烟煤与污泥质量比为1∶1,水热碳化温度为160℃时,所制备的水热炭经活化后,其在吸附温度为120℃时,对SO_(2)的吸附量为52.2 mg/g,且随着水热碳化温度升高,其吸附量有所下降,共水热炭相比于单一水热炭对CO_(2)和SO_(2)的吸附性能更好。研究结果可为低阶煤和污泥清洁高效利用和低成本CO_(2)、SO_(2)吸附剂开发提供理论依据。