材料科学前沿-氢能与储氢材料课件.ppt

1、材料科学前沿汇报氢能与储氢材料Hydrogen Energy&Hydrogen Storage Materials董汉武2018年6月22日1 能源有什么重要性？为什么要发展氢能？成熟的氢能技术有哪些？什么是储氢材料？不同储氢材料各有什么特点（优缺）？储氢材料面临什么挑战？储氢材料的开发思路有哪些？2报告前的疑问 氢能简介与储氢方法 评估/表征储氢方法/材料 储氢材料的历史沿革与发展现状 储氢材料前沿研究领域 储氢材料发展展望报告概要3 What is ENERGY?4话题 能源 Why(is)ENERGY(so important)?能源是人类生存、社会延续与进化的物质基础！能源是人类生存、

2、社会延续与进化的物质基础！5话题 能源 Organic Energy Economy 有机能源经济 Fossil Fuel Energy Economy 化石能源经济What is the future?Hydrogen Energy Economy?6话题 能源与社会经济1 氢能简介Introduction to the Hydrogen Energy7 化石能源？储量？氢能？为何要发展氢能？8http:/ 11 October 2015.能量总量、功率！9理想中的终极氢能？The Ultimate Hydrogen Energy？理想中的终极氢能？The Ultimate Hydrogen

3、 Energy？10 可控核聚变.关键材料承受高温高压等离子体我们今天要谈的或可称为“常规氢能”11氢能与交通工具高热值洁净零排发环境友好气候问题？成本？动力、操控性？12广州：BMW7系未来氢经济社会的设想13Typically,6 kg of hydrogen is able to allow a light-duty vehicle to run for 500 km.直接利用形式主要为电，氢为二次能源载体。14 混合动力汽车？(HEV,Hybrid Electric Vehicle)电动汽车？(EV,Electric Vehicle)氢能燃料电池汽车？（HFCV,Hydrogen Po

4、wered Fuel Cell Vehicle)成本，整车效率（车重），续航里程，补充能源速度，安全性15美国的政策1617近段时间的氢能应用发展中國國務院總理李克強，今參訪位於北海道苫小牧市的豐田汽車子公司，在豐田汽車社長豐田章男導覽下，參觀氫燃料車。18近段时间的氢能应用发展19近段时间的氢能应用发展氢能应用链示例 三大技术环节：制氢，储氢储氢，用氢20制氢储氢用氢US DOE 2020系统储氢性能目标：gravimetric capacity 5.5wt%volumetric capacity 40g/Loperating temperature-4060Cmax.delivery pr

5、essure 12 bar常温常压下氢气体积密度：0.089 g/L6 kg氢气的体积：5米直径的球提升压力至700 bar:150 LNow,the academic part21ENERGY?2223用氢简介2425储氢-关键的中间环节！基本储氢方法如下26车载气态储氢罐1液态储氢罐2固态材料储氢 3金属镁体积密度低需要高压力压缩氢气需要较高能耗体积密度高(70g/L)压缩并冷却液化需要更高能耗（约1/3所制得液氢的燃烧热值）储氢密度潜在能力高但综合性能距离目标值仍然很大Compressed hydrogen vs.materials-based hydrogen storage27Ste

6、tson N.An overview of U.S.DOEs activities for hydrogen fuel cell technologies,2/27/2012,Clearwater,Floride,America.物理吸附储氢基于分子间作用力需要较低温度和较高压力 化学吸附储氢基于原子间的化学键合力需要较高温度实现循环28基于材料的储氢2 评估储氢方法/材料Properties Assessment for Hydrogen Storage Materials2930不同储能方法的储能密度（重量密度，体积密度）不同储氢方法/材料的储氢能力比较31看点：看点：体积密度重量密度可逆

7、性 较理想的储氢反应温度：100C附近 较理想的储氢反应压力：10 atm 左右32储氢材料的热力学性能US DOE 2020系统储氢性能目标：gravimetric capacity 5.5wt%volumetric capacity 40g/Loperating temperature-4060Cmax.delivery pressure 12 bar储氢材料的热力学性能33(a)T1T2T3平台区域放氢吸氢滞后T2T3p3p2p1Xplnp1/TOABOx斜率=H/R截距=-S/R(b)T1The vant Hoffequation储氢材料的动力学性能34 Kinetic propert

8、ies Kinetic process Different kinetic models Reaction barrier:Activation energy More difficult duringdehydrogenation thanhydrogenation气相扩散表面解离H2固相扩散H金属-氢反应过程中体系自由能变化反向正向 动力学，速度功率 可逆性，可逆程度 材料工作寿命 其他实际因素考虑：成本，安全储氢材料的动力学与其他性能至今仍未有完美的储氢材料！3 储氢材料的历史沿革与发展现状Introduction to the Hydrogen Energy36传统合金储氢材料37 A

9、B5-LaNi5(MmNi5-xMx)储氢量储氢量1.5wt%、动力学好、较贵、动力学好、较贵 AB2-ZrCr2(Ti1-xZrxCrMn)储氢量储氢量2.0wt%、动力学好、昂贵、难活化、动力学好、昂贵、难活化 AB FeTi 储氢量储氢量1.8wt%、动力学好、易中毒、歧化、动力学好、易中毒、歧化 A2B-Mg2Ni 储氢量储氢量3.6wt%、动力学差、动力学差 Mg 储氢量储氢量7.6wt%、动力学很差、动力学很差（约（约400oC、30 atm)Ni-MH Batteries近年发展的储氢材料-物理吸附材料38 Carbon,MOFs,zeolites,porous polymers

10、,Adsorption enthalpies:2-5 kJ/mol H2 Liquid N2 temperature Capacity limited by specific surface area(SSA),pore structure and pore sizes Ideal materials:High SSA,pore size 1 nm Better measured with up to 210 MPa H2,using IUPAC“excess hydrogen material capacity”.Goal:higher capacity up to 10wt%at 2-3M

11、PaH2 uptake capacities at 77 K and BET surface areas of various MOFs39A plot showing the relationship between H2 uptake capacities at 77 K and BET surface areas of various MOFs.Low pressure is 1 bar and high pressures are in the range of 10e90 bar.近年发展的储氢材料-化学储氢材料40 Hydrolytic Hydride Systems 氢化物水解体

12、系 NaBH4:Usually irreversible Reversible Hydride Systems 可逆储氢体系 Interstitial Metal hydridesAB5(LaNi5),AB2(A=Ti,Zr,Mg;B=V,Cr,Fe,Mn),AB3 Salt-like MgH2:high cap.,low cost,env.friendly,good reversibility NaAlH4 Irreversible Hydride Systems 非可逆储氢体系 LiAlH4,LiBH4,Mg(BH4)2 Amine-Borane Adducts:NH3B3H7,胺硼烷 A

13、mides/Imides氨基化合物，酰亚胺等储氢材料前沿研究领域The Frontier！41CHALLENGES!42We always want high capacity systems,but:Desirable stability?Too unstable:Mg(AlH4)2(circa 0 kJ/mol H2)Or too stable:MgH2,LiBH4 Reversibility?Regeneration of LiBH4 Suitable kinetics?MgH2431.Nano-size effect support from theoretical calculati

14、ons Seek for theoretical insights to guide further experimental纳米线结构Hydrogen storage with A2_MgH2 nanowire(0.85 nm)is possible at room temperature.Nano-size effect-continue44 Experimental results:nano-confinementMelt-infiltration(熔融渗透)Particle size can beas low as 25 nm No thermodynamic changeobserv

15、ed yet.Much faster kineticsfor grain size 1030 nm of the Mg0.95Ni0.05 sampleNano-size effect:nano-confinement continue45Impregnation(湿化学浸渍)Part of the Mg particles are small enough(2 nm)to alter thermodynamics4 times faster kinetics than ball milled MgH245Nano-size effect:nano-confinement continue46

16、 Metallic Mg nanocrystals(NCs)in a gas-barrier polymer matrix允许H2但却阻止水和氧分子透过的高分子薄膜包覆Mg纳米颗粒十分巧妙地解决了氧化威胁和纳米结构稳定性的问题Nano-size effect from ball milling47 Preparation of nano-crystalline Mg/MgH2 by ball mill Enhance kinetics Size limitation:20100 nm Far from theoretical predicted level Significantly alte

17、red thermodynamics will not be observed.48 Thermo stability/cycle life of nano-particles Archiving size 12 nm is very hardThus hard to alter thermodynamics Supporting materials lower total capacity Entropy effect becomes significant but is not studied wellZhao-Karger等人直接对3 nm以下的MgH2颗粒放氢过程进行测试发现反应焓降至

18、63.80.5 kJ/mol，熵为117.20.8 J/mo由于熵也发生较明显变化，经纳米限域后的样品1 bar H2时的放氢温度较粗晶MgH2仅下降11CZhao-Karger Z.R.,Hu J.J.,Roth A.,et al.Altered thermodynamic and kinetic properties of MgH2 infiltrated in microporous scaffoldJ.Chemical Communications,2010,46:8353-8355.Problems for utilizing nano-size effect492.Doping/c

19、atalytic effect掺杂的多相结构、界面结构The dehydrogenation of MgH2 with 1 mol%Nb2O5 and formation of nanosizedMg particles were observed at 150 C502.Doping/hydrogen pump/spill overHydrogen pump catalyze both H absorbing and desorbingPd,YNi,CeHx (easy H2 absorbing),YH2 YH3,ReHx ReHySpill over:单个氢分子在催化剂(AB5)颗粒表面解

20、离成两个氢原子，氢原子可以选择被“溢流”到与合金颗粒物理接触的材料的表面，同时也可以扩散进入合金颗粒晶格当中Both increase kinetic properties513.External constraint applied via multilayer thin film多层薄膜结构Pd/Mg/Ti/Mg/Ti设计层构成为Substrate/Ti(10nm)/Mg(dMg)/X(10nm)/Pd(10nm)(X为过渡金属Pd,Ni,Ti,V,Nb，dMg为镁层厚度，分别为10,15,20,30和40nm)一系列的多层薄膜，证明与Mg形成合金的过渡金属如Pd和Ni覆盖对Mg层可构成弹

21、性夹紧而极大提升Mg层的吸氢平台压力524.Via solid solution and intermediate phaseH变小变小反应可逆反应可逆Mg(In)的固溶体在高温300C以上吸氢，生成MgH2和富In的相；300C放氢过程中，MgH2放氢后与相又能反应生成初始成分的Mg(In)固溶体；吸/放氢反应的焓比纯Mg的减少了约10 kJ/mol，实现了对热力学的调控。535.Binary,ternary,multinary alloyingHydrogen Combustion SynthesisMg2NiH4,64kJ/mol H2,3.6wt%HMg-Cu,Mg-Al alloys

22、Mg-Y-Ni alloysIncreased kineticsLowered formation enthalpyMay suffer from irreversible reactionLowered storage density54 Other methods existBut NONE of the above has made some kind of material reaching a satisfactory level of performance.Fundamental problems existDifferent application fields demands

23、 different properties储氢材料发展展望Looking Foward5556 Suitable hydrogen storage methods/materials are critical to establish hydrogen energy infrastructure.No material/method has reached satisfactory level of performance.Fundamental insights and proper design of storage system are two keys to more viable h

24、ydrogen energy.Para-Hydrogen,Ortho-Hydrogen57https:/en.wikipedia.org/wiki/Spin_isomers_of_hydrogenThe interest in the concept of storing hydrogen in para form stems from the fact that para-hydrogen has a lower energystate than ortho-hydrogen.It is therefore theoretically easier to store hydrogen in the para form.报告完毕，谢谢同学们！欢迎提问、批评与指正！58