锂离子电池富锂正极材料Li[Li0.2Ni0.16Mn0.56Co0.06Al0.02]O2的合成和电化学性能

用溶胶-凝胶法首次合成了富锂正极材料Li[Li0.2Ni0.16Mn0.56Co0.06Al0.02]O2,它可以看成是Li[Li1/3Mn2/3]O2和LiNi0.4Mn0.4Co0.15Al0.05O2形成的固溶体。XRD测试表明该材料具有ɑ-NaFeO2层状结构,用SEM观察材料粒径为100nm左右。充放电测试得到,材料在2～4.8V范围内,0.1C的电流下,20℃时,首次放电比容量达221.8mAh/g,库伦效率为85.3%;55℃时,首次放电比容量达281.7mAh/g,库伦效率为93.0%;且该材料具有很好的循环稳定性及优良的倍率性能。通过循环伏安测试分析了该材料的充放电机理。     

新型TiO2（B）/碳复合纳米线负极材料电化学特性研究

以锐钛矿TiO2粉末为原料,通过简单的两次水热及氩气气氛下热处理工艺,制备出新型TiO2(B)/碳一维复合纳米线材料。研究结果表明该复合纳米线主要是由TiO2(B)所组成,其外层包覆一层无定形碳以形成特殊的一维壳/核结构;这种特殊一维壳/核结构和化学组成在诸多领域都将会有着极其广泛应用。本文锂离子电池测试结果证实该复合纳米线电极具有超高的可逆循环电池容量和倍率充放电容量,在30 mAg-1充放电速率下,该TiO2(B)/碳一维壳核结构材料100圈循环后容量高达560 mAhg-1;在750 mAg-1充放电速率下,充放电容量达到200 mAhg-1。鉴于其优良的电化学性能,该一维复合结构材料有望成为下一代最有前途的锂离子电池电极材料。     

锐钛矿/TiO2（B）复合纳米线制备及其锂存储研究

以锐钛矿TiO2粉末为原料,通过碱液水热反应并辅以酸洗和热处理工艺,制备出一致性良好的锐钛矿/TiO2（B）一维复合纳米线材料。研究结果表明该复合纳米线在30mA/g（0.1C）充放电速率下,该锐钛矿/TiO2（B）一维壳核结构材料100圈循环后容量高达196mAh/g;在4500mA/g（15C）充放电速率下,充放电容量达到125mAh/g。由于其优良的电化学性能,该一维复合结构材料有望成为下一代最有前途的锂离子电池电极材料。     

锂离子在正极材料LiNi1/3Co1/3Mn1/3O2中扩散系数的测定

对改进固相反应法合成的锂离子电池层状正极材料LiNi1/3Co1/3Mn1/3O2,利用XRD,SEM对粉体进行了物相结构和形态表征.当电池充放电时,设定电流密度为120mA/g,电压在2.75～4.5V区间,20次循环后放电比容量为164.5mAh/g.在开路电压到4.5V作为材料的锂离子扩散系数测试电压区间进行CITT循环测试,测定了材料在不同电压,不同循环下的扩散系数,测得扩散系数在10-11～10-12 cm2/s范围内;当电压E=4.3V时扩散系数达到最大值2.8×10-11 cm2/s,随着充放电循环的进行,Li+固相扩散系数先增大后减小.     

层状Li0.7CoxMn1-xO2正极材料的合成与电性能研究

通过离子交换法在空气气氛中合成了具有O2型结构特征的掺Co3+型层状正极材料Li0.7CoxMn1-xO2, 用XRD、SEM、粒度分析和电性能测试等手段研究了煅烧温度和掺钴量对前驱体碱锰青铜及目标正极材料性能的影响.在900℃煅烧16h合成的前驱体Na0.7Co0.2Mn0.8O2具有P2型层状碱锰青铜结构特征, XRD特征峰尖锐.样品Li0.7Co0.2Mn0.8O2 在2.25～4.20V首次放电容量为162mAh·g-1, 循环40次后, 容量保持率在90%以上; 充放电曲线光滑, 仅存在2.70～2.90V唯一充放电平台, 在循环过程中未发生可逆相变.     

不同沉淀剂对所制备的LiNi0.8Co0.1Mn0.1O2正极材料性能影响的研究

采用共沉淀-高温固相烧结法,控制合成条件,以不同的沉淀剂(Na2CO3、NaOH)制备出正极材料。通过XRD、SEM及电池测试系统对不同沉淀剂制备的正极材料进行结构、形貌和电化学性能的表征,对比两者存在的优缺点。研究结果表明,以NaOH为沉淀剂制备的正极材料有更好的层状结构,形貌也更好,充放电性能和倍率性能也较好。其首次放电比容量达到了187.9mAh/g,最高可达196.2mAh/g,50次充放电循环后,容量保持率为81.6%;以Na2CO3为沉淀剂制备的正极材料的放电比容量较低,但容量保持率较高,为85.3%。     

NiCo2O4/C复合电极材料的制备以及超级电容性能

采用化学共沉淀法合成了纳米级NiCo2O4/C复合材料,并以X射线衍射(XRD)、扫描电镜(SEM)对样品进行了结构和形貌的表征,结果表明,合成的复合材料为立方尖晶石结构,其粒径大小为30～40nm,颗粒呈球形且分布均匀。循环伏安(CV)、恒电流充放电测试表明,NiCo2O4/C复合材料在6mol/LKOH水系电解液中表现出优异的超级电容特征,在0～0.9V的电位范围内,NiCo2O4/C电极材料比电容量可高达290.49F/g,并具有良好的可逆性和优异的循环性能。     

LiFePO4材料的制备与电池性能的研究

通过固相法合成了裂解碳包覆的具有亚微米球形颗粒团簇微结构的LiFePO4粉体材料.材料中裂解碳百分含量为5.01%,一次颗粒粒径在200～600nm,团簇体粒径在10μm左右.在0.1、0.2、0.5和1C的充放电速率下,研究了材料的比容量和循环稳定性的变化.当充放电速率＜1C时,随着充放电速率的增大,材料的充放电平台和比容量并不随速率的增大而发生较大变化,当充放电速率≥1C时,材料的充放电电压平台迅速升高(充电)或降低(放电),比容量也有较大的降低;随着充放电次数的增加,材料的比容量有所增加,然后趋于稳定.在30个循环后材料的放电比容量分别为131.7、129.1、123.5和114.4mAh/g.     

Li+掺杂提升高钠P2-Na0.85Mn2/3Ni1/3O2正极材料的电化学性能

P2型层状氧化物正极材料在充放电过程中容易产生Na⁺/空位有序性和P2到O2/OP4相位转变,导致多个充放电平台。低钠P2型层状氧化物在深度脱钠时容易造成材料结构不稳定,限制了可逆容量。这些缺陷造成P2型层状氧化物正极材料倍率性差和容量快速衰减。为了抑制Na⁺/空位有序性和相位转变,采用溶剂热法结合Li⁺掺杂(0,0.05%,0.1%,0.15%摩尔分数)制备出了无多个电压平台和无相位转变的P2型Na_0.85Mn_0.6Ni_0.3Li₀₁O₂(NMNL-0.1)层状氧化物正极材料。NMNL-0.1正极材料在2 C电流密度下进行200次循环后的容量保持率为83%,而未掺杂锂的P2型Na_0.85Mn_2/3Ni_1/3O₂(NMN)样品的容量保持率为30%。在20 C电流密度下NMNL-0.1正极材料的放电比容量为62.5 mAh·g<...     

炭黑包覆Al2O3掺杂LiMn2O4正极材料的研究

使用醋酸锂、醋酸锰和氧化铝为原料,采用高温固相法合成掺杂Al离子的LiMn2O4二级产物。合成化学计量比为n(Li)∶n(Mn)∶n(Al)=1.3∶1.9∶0.1。首次烧结温度450℃,烧结时间4h;二次烧结温度750℃,煅烧时间为40h。合成样品采用XRD进行材料表征。测试结果表明:合成样品为尖晶石结构,结晶度较高。所得样品使用炭黑包覆处理,并制成实验性电池,对其进行交流阻抗测试(EIS)分析、循环伏安特性(CV)测试、充放电及循环性能测试分析。实验结果表明:包覆后的正极材料改善了LiMn2O4的大电流充放电性能,该材料在0.5C的首次放电比容量为93mAh/g;包覆材料增强了在大电流充放电下的容量保持率,极大地改善了电池的循环性能,该材料在充放电倍率为0.2C时,32次循环后的容量保持率为92.5%。     

喷雾干燥法制备富锂正极材料及其电化学性能

用喷雾干燥法制备Li_1.2Mn_0.54Ni_0.13Co_0.13O₂富锂正极材料并表征其结构、形貌以及电化学性能,研究了烧结温度对材料电化学性能的影响。结果表明：这种正极材料具有良好的层状结构,一次颗粒粒径为100 nm左右且分布均匀,样品的首次放电比容量为220.2 mAh/g,库伦效率为72.5%,18个循环后容量保持率为96.8%。电化学阻抗和循环伏安特性的测试结果表明,这种正极材料具有良好的电化学性能。     

微波场下纳米Mg-Al-LDHs及PO_4~(3-),P_2O_7~(4-)柱撑Mg-Al层状双氢氧化物的合成

用微波加热反应-变速滴加共沉淀法合成了[Mg-Al-CO3]纳米层状双氢氧化物,并以[Mg-Al-CO3]纳米层状双氢氧化物为前体,用微波加热反应-离子交换法制备了PO43-,P2O74-柱撑Mg-Al层状双氢氧化物。该法合成的[Mg-Al-CO3]纳米层状双氢氧化物的粒径约为10-40nm。讨论了微波和变速滴加碱液的速度对纳米层状双氢氧化物的合成的影响。用FT-IR、TEM与XRD对产物进行了表征,结果表明在微波加热反应的条件下可在短时间内用PO43-,P2O74-彻底交换CO32-。     

Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

The interconnect half‐pitch size will reach ≈20 nm in the coming sub‐5 nm technology node. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be >4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross‐section and they are much more resistive than Cu, the effective conductance of an ultrascaled interconnect will be compromised by the thick bilayer. Therefore, 2D layered materials have been explored as diffusion barrier alternatives. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back‐end‐of‐line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. Here, a 2D layered tantalum sulfide (TaS_x ) with ≈1.5 nm thickness is developed to replace the conventional TaN/Ta bilayer. The TaS_x ultrathin film is industry‐friendly, BEOL‐compatible, and can be directly prepared on dielectrics. The results show superior barrier/liner properties of TaS_x compared to the TaN/Ta bilayer. This single‐stack material, serving as both a liner and a barrier, will enable continued scaling of interconnects beyond 5 nm node.     

From two-dimensional metal-organic coordination networks to near-infrared luminescent PbS nanoparticle/layered polymer composite materials

Two-dimensional (2-D) layered metal-organic coordination (lead methacrylate (LDMA)) networks have been prepared in aqueous solution under mild conditions and their structure determined by single crystal diffraction. As the ligand used in our experiments is easily to polymerized, these metal-organic coordination layers are therefore employed as precursors to fabricate cross-linked polymer layered materials through γ-irradiated polymerization. The stabilities of the samples are significantly improved after γ-irradiation. To our knowledge, this is the first time that covalent bonded polymer layered structures have been fabricated without the assistance of added surfactant or template. Such layered polymer materials cannot only act as alternative to layered inorganic materials in some caustic environments, but also allows the generation of PbS nanoparticles (NPs) without aggregation in the polymer matrix. By exposing the polymer layer to H₂S gas at room temperature, uniform PbS nanoparticles with an average size of about 6 nm are generated in situ. In addition, the resulting PbS NPs exhibit near-infrared (NIR) luminescent properties, which suggests the composite materials may be useful as active optical elements at communication wavelengths from 1300 to 1550 nm. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. This article is published with open access at Springerlink.com     

Nanocomposite Films of MoO3 Xerogel with Poly (ethylene oxide) (PEO) Intercalation

(PEO)(x)MoO3.nH(2)O(x=0 similar to2) nanocomposite films were prepared by ion exchange method and polymer solution direct intercalation in sol-gel route. The synthesis and structure of the films were investigated by XRD, DSC, FTIR, etc. The results show that MoO3 xerogel has a layered structure, which arranges in b-direction. The interlayer distance Of MoO3 xerogel increases from 0.690 nm at x=0 to 1.308 nm at x=2 after heat treatment. PEO can be completely intercalated into the interlayer at x=0.5 similar to1 and has strong interaction with MoO3 host.     

镁铝层状双金属氢氧化物的制备及表征

分别以氨水和氢氧化钠为沉淀剂,采用共沉淀法合成Mg-Al层状双金属氢氧化物,对产物的晶相、形貌和结构进行表征,采用正交实验法研究金属离子比例、反应温度、pH值等因素对产物层间距及层板生长机制的影响。结果表明,以氨水作为沉淀剂,Mg与Al物质的量比为2∶1,pH值为9.5,反应温度为40℃时,得到结晶度高,物相纯净且层间距d(003)达0.882 1 nm的层状双金属氢氧化物。     

表面活性剂对纳米Sb2O3和纳米 Sb2O3/云母分散性的影响

以片状云母作为微反应器制备了纳米Sb2O3／云母复合物，并用XRD、TEM进行了表征．研究了表面活性剂对纳米Sb2O3颗粒、纳米Sb2O3／云母复合物的粒子性能及粒度分布的影响，并对二者进行了比较．结果表明：纳米Sb2O3被十六烷基三甲基溴化铵处理后，在云母层间均匀生长，形成的纳米Sb2O3分散性好，粒度分布窄．平均粒径约为5nm，比不加云母制备的纳米Sb2O3小30nm．     

NbSe2纤维的制备及其摩擦学行为

为探索新型润滑材料,将Nb和Se密闭在石英容器中,高温下反应,得到NbSe₃,将其研磨、干燥后在氩气保护气氛中于700℃分解,制得直径为80 nm～160 nm的NbSe₂纤维。用扫描电子显微镜、透射电子显微镜、X射线衍射仪等检测产物的相组成及形貌。利用UTM-2型微观摩擦试验机测试其作为润滑油添加剂的摩擦学性能。结果表明,在室温大气下,添加NbSe₂纤维的润滑油较纯润滑油和添加普通NbSe₂粉末的润滑油有较好的润滑能力和抗磨性能, 其主要原因是NbSe₂纤维具有独特稳定的结构。将纳米NbSe₂与青铜粉混合,制备出铜基复合材料,摩擦实验证明,NbSe₂纤维能明显降低铜基复合材料的摩擦系数,这可能归因于摩擦过程中在摩擦表面形成的一层润滑膜。     

Carbon-supported growth of cross-linked platinum nanowires by surfactant templating and their elecrochemical characterization

Platinum/carbon (Pt/C) composite materials were prepared by the hydrazine reduction of H2PtCl6 confined to a mixed surfactant lytropic liquid crystal (LC)/C mixture with varying amounts of water. The reaction at relatively low water contents successfully yielded cross-linked Pt nanowires with wire-widths of 2-5 nm. The novel Pt nanostructure is believed to be from poorly hydrated hexagonal domains formed together with layered domains by the phase separation of the precursory LC mixture in the presence of carbon. Electrochemical measurements using cyclic volutammetry and membrane electrode assemblies revealed that the cross-linked nanowired Pt/C composite exhibits fairly high electrocatalytic activity for oxygen reduction reaction, as well as a high performance as the cathode material for polymer electrolyte fuel cells.     

丙烯酸根离子柱撑Mg-Al-LDHs水滑石的合成及紫外屏蔽性能研究

以Mg-Al水滑石为前体,采用返混沉淀法进行插层组装合成丙烯酸根离子柱撑水滑石.利用红外光谱、X射线衍射、紫外分光光度法对其结构和性能进行了表征.结果表明,丙烯酸根阴离子可以插入纳米Mg-Al水滑石层间,其层间距由0.76nm增大到1.17nm,形成具有超分子结构的丙烯酸根离子柱撑水滑石,并模拟出其分子结构模型.这种新的插层结构材料可以增强其紫外吸收性能,进而使得其紫外屏蔽作用增强,从而成为一种集屏蔽和吸收双重功能的新型无机-有机复合紫外阻隔材料.