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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
2、！,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,C%, H%,1 氢能简介,Introduction to the Hydrogen Energy,7,化石能源？储量？氢能？,为何要发展氢能？,OR,8,http:/ Accessed 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？T
3、he Ultimate Hydrogen 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,13,Typically, 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, Electri
4、c Vehicle)氢能燃料电池汽车？（HFCV, Hydrogen Powered 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,16,17,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，用氢,20,US DOE 2020系统储氢性能目标：gravimetric capacity 5.5wt%volumetric capacity 40g/
5、Loperating temperature -4060Cmax. delivery pressure 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 L,Now, the academic part制氢简介,21,22,23,用氢简介,24,25,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
6、大,Compressed hydrogen vs. materials-based hydrogen storage,27,Stetson 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 St
7、orage Materials,29,30,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：体积密度重量密度可逆性,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
8、,T2,T3,p3,p2,p1,X,p,lnp,1/T,O,A,B,O,x,斜率=H/R截距=-S/R,(b),T1,ln = ,The vant Hoffequation,Mg+ H 2 MgH 2 +75 kJ mol 1 , 0.1MPa at 300 ,储氢材料的动力学性能,34,Kinetic propertiesKinetic processDifferent kinetic modelsReaction barrier:Activation energyMore difficult duringdehydrogenation thanhydrogenation,气相扩散,表面解离
9、,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 Energy,36,传统合金储氢材料,37,AB5 - LaNi5 (MmNi5-xMx) 储氢量1.5wt%、动力学好、较贵 AB2 - ZrCr2 (Ti1-xZrxCrMn) 储氢量2.0wt%、动力学好、昂贵、难活化 AB FeTi 储氢量1.8wt%、动力学好、易中毒、歧化 A2B - Mg2Ni
10、储氢量3.6wt%、动力学差 Mg 储氢量7.6wt%、动力学很差 （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, Adsorption enthalpies: 2-5 kJ / mol H2Liquid N2 temperatureCapacity limited by specific surface area (SSA), pore structure and pore sizesIdeal materials: High SSA, pore siz
11、e 1 nmBetter measured with up to 210 MPa H2, using IUPAC “excess hydrogen material capacity”.Goal: higher capacity up to 10wt% at 2-3MPa,H2 uptake capacities at 77 K and BET surface areas of various MOFs,39,A plot showing the relationship between H2 uptake capacities at 77 K and BET surface areas of
12、 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 氢化物水解体系NaBH4:Usually irreversibleReversible 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: hig
13、h cap., low cost, env. friendly, good reversibilityNaAlH4Irreversible Hydride Systems 非可逆储氢体系LiAlH4, LiBH4, Mg(BH4)2Amine-Borane Adducts: NH3B3H7, 胺硼烷Amides/Imides氨基化合物，酰亚胺等,储氢材料前沿研究领域,The Frontier！,41,CHALLENGES!,42,We always want high capacity systems, but:Desirable stability?Too unstable: Mg(AlH4
14、)2 (circa 0 kJ / mol H2)Or too stable: MgH2, LiBH4Reversibility?Regeneration of LiBH4Suitable kinetics?MgH2,43,Nano-size effect support from theoretical calculationsSeek 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
15、temperature.,Nano-size effect - continue,44,Experimental results: nano-confinementMelt-infiltration (熔融渗透)Particle size can beas low as 25 nm No thermodynamic changeobserved yet.Much faster kineticsfor grain size 1030 nm of the Mg0.95Ni0.05 sample,Nano-size effect: nano-confinement continue,45,Impre
16、gnation (湿化学浸渍)Part of the Mg particles are small enough ( 2 nm) to alter thermodynamics4 times faster kinetics than ball milled MgH2,45,Nano-size effect: nano-confinement continue,46,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,
17、Nano-size effect from ball milling,47,Preparation of nano-crystalline Mg/MgH2 by ball mill Enhance kineticsSize limitation: 20100 nmFar from theoretical predicted levelSignificantly altered thermodynamics will not be observed.,48,Thermo stability / cycle life of nano-particlesArchiving size 12 nm is
18、 very hardThus hard to alter thermodynamicsSupporting materials lower total capacityEntropy effect becomes significant but is not studied well,Zhao-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11C,Zhao-Karger Z.R., Hu J.J., Roth A
19、., et al. Altered thermodynamic and kinetic properties of MgH2 infiltrated in microporous scaffoldJ. Chemical Communications, 2010, 46: 8353-8355.,Problems for utilizing nano-size effect,49,Doping/catalytic effect,掺杂的多相结构、界面结构,The dehydrogenation of MgH2 with 1 mol % Nb2O5 and formation of nanosized
20、Mg particles were observed at 150 C,50,Doping/hydrogen pump/spill over,Hydrogen pump catalyze both H absorbing and desorbingPd, YNi, CeHx (easy H2 absorbing), YH2 YH3, ReHx ReHy,Spill over: 单个氢分子在催化剂(AB5)颗粒表面解离成两个氢原子，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 properties,51,
21、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层可构成弹性夹紧而极大提升Mg层的吸氢平台压力,52,Via solid solution and intermediate phase,H变小反应可逆,Mg(In)的固
22、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。,53,Binary, ternary, multinary alloyingHydrogen Combustion SynthesisMg2NiH4, 64kJ/mol H2, 3.6wt% HMg-Cu, Mg-Al alloysMg-Y-Ni alloys,Increased kineticsLowered formation enthalpyMay suffer from irr
23、eversible reactionLowered storage density,54,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 different properties,储氢材料发展展望,Looking Foward,55,56,Suitable hydrogen storag
24、e 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 hydrogen energy.,Para-Hydrogen, Ortho-Hydrogen,57,https:/en.wikipedia.org/wiki/Spin_isomers_of_hydrogen,The 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,
