Co3(HCOO)6@rGO 作为锂离子电池负极材料的研究

MOFs材料作为一类新型的锂离子电池电极材料而受到广泛关注和研究. 作者通过溶液扩散法将Co₃(HCOO)₆原位负载在 rGO（还原氧化石墨烯）上制备出Co₃(HCOO)₆@rGO复合材料. 将Co₃(HCOO)₆@rGO作为锂离子电池负极材料,以500 mA·g^-1的电流密度恒电流充放电循环 100 周后,仍然保持有 926 mAh·g^-1 的比容量,亦表现出很好的倍率性能. 循环伏安和X-射线光电子能谱测试表明,Co₃(HCOO)₆@rGO材料上的Co²⁺和甲酸根在充放电过程中均发生可逆的电化学反应. 对比同样采用溶液扩散法合成的 Co₃(HCOO)₆ 的测试结果发现,rGO起到活化甲酸根的电化学反应的作用,同时也改善了Co₃(HCOO)₆的倍率性能. 将MOFs材料与rGO复合为优化 MOFs 材料的电池性能提供了一个新思路.     

Synthesis of iron oxide cubes/reduced graphene oxide composite and its enhanced lithium storage performance

Fe₃O₄ is considered as a promising electrode material for lithium-ion batteries(LIBs) due to its low cost and high theoretical capacity(928 mAh/g).Nevertheless,the huge volume expansion and poor conductivity seriously hamper its practical applications.In this study,we use a facile hydrothermal reaction together with a post heat treatment to construct the three-dimensional heterostructured composite(Fe₃O₄/rGO) inwhich reduced graphene oxide sheets wraped the Fe₃O₄ submicron cubes as the conductive network.The electric conduction and electrode kinetics of lithium ion insertion/extraction reaction of the composite is enhanced due to the assist of conductive rGO,and thus the Listorage performance is obviously improved.The composite exhibits a reversible charge capacity of772.1 mAh/g at the current density of 0.1 A/g,and the capacity retention reaches 70.3% after400 cycles at0.5 A/g,demonstrating obviously higher specific capacity and rate capability over the Fe₃O₄ submicron cubes without rGO,and much superior cycling stability to the parent Fe_2 O_3 submicron cubes without rGO.On the other hand,as a synergic conductive carbon support,the flexible rGO plays an important role in buffering the large volume change during the repeated discharge/charge cycling.     

Se-decorated SnO2/rGO composite spheres and their sodium storage performances

SnO₂ is considered a promising anode material for sodium-ion batteries due to its high theoretical capacity and low cost.However,the poor electrical conductivity and dramatic volume variation during cha rge/discharge cycling is a major limitation in its practical applicability.Here we propose a simple onepot spray pyrolysis process to construct unique pomegranate-like SnO₂/rGO/Se spheres.The ideal structural configuration of these architectures was effective in alleviating the large volume variation of SnO₂,besides facilitating rapid electron transfer,allowing the devised anode to exhibit superior sodium sto rage performances in terms of capacity(506.7 mAh/g at 30 mA/g),cycle performance(397 mAh/g after100 cycles at 50 mA/g) and rate capability(188.9 mAh/g at an ultrahigh current density of 10 A/g).The experimental evidence confirms the practical workability of p-SnO₂/rGO/Se spheres in SIBs.     

磷酸钒锂/石墨烯复合正极材料的制备及表征

通过三聚氰胺甲醛树脂(MR)中的羟基与石墨烯氧化物(GO)中的羧基发生的沉淀反应来制备功能化的氧化石墨烯前驱体,然后利用溶胶-凝胶及高温热处理方法制备磷酸钒锂/石墨烯复合材料,利用此材料制备了电池电极,并对电极材料进行了结构和电化学表征。结果表明,所得磷酸钒锂为单斜晶系结构,石墨烯堆叠程度显著降低,也有效避免了磷酸钒锂颗粒的团聚,提高了材料的电化学性能。电池的充放电曲线极化较小,在3.0~4.3 V的区间内20 C倍率仍有86 mA·h/g的可逆容量。0.1 C循环100次后容量为119.7 mA·h/g,容量保持率94%。在3.0~4.8 V的高电压区间,10 C倍率下可逆容量80 mA·h/g,0.1 C循环100次后仍有145.6 mA·h/g的可逆容量。优异的循环和倍率性能以及较低的碳含量符合锂离子正极材料实用的要求。     

Microwave assisted hydrothermal synthesis of tin niobates nanosheets with high cycle stability as lithium-ion battery anodes

SnNb₂O₆ and Sn₂Nb₂O₇ nanosheets were synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. Compared with Sn₂Nb₂O₇ and the previously reported pure Sn-based anode materials, the SnNb₂O₆ electrode exhibited outstanding cycling performance.     

Controlling the morphology,size and phase of Nb2O5 crystals for high electrochemical performance

Herein, the nano-sized niobium pentoxide (Nb₂O₅) with different morphologies and phase structures are synthesized through a very simple thermal treatment method, including the pseudohexagonal Nb₂O₅ nanosheets and pseudohexagonal Nb₂O₅ nanoparticles, orthorhombic Nb₂O₅ nanoparticles. The synthesized pseudohexagonal Nb₂O₅ nanosheets and orthorhombic Nb₂O₅ nanoparticles exhibit better cycling and rate performance than the pseudohexagonal Nb₂O₅ nanoparticles due to the different morphologies and phase structures.     

原位限域生长策略制备有序介孔碳负载的超小MoO3纳米颗粒

采用原位限域生长策略制备了一系列有序介孔碳负载的超小MoO₃纳米颗粒复合物(OMC-US-MoO₃). 其中, 有序介孔碳被用作基质来原位限域MoO₃纳米晶的生长. 依此方法制备的MoO₃纳米晶具有超小的晶粒尺寸(<5 nm), 并在介孔碳骨架内具有良好的分散度. 制得的OMC-US-MoO₃复合物具有可调的比表面积(428~796 m²/g)、 孔容(0.27~0.62 cm³/g)、 MoO₃质量分数(4%~27%)和孔径(4.6~5.7 nm). 当MoO₃纳米晶的质量分数为7%时, 所得样品OMC-US-MoO₃-7具有最大的孔径、 最小的孔壁厚度和最规整的介观结构. 该样品作为催化剂时, 表现出优异的环辛烯选择性氧化性能.     

Ni3S2@碳纳米管复合材料的制备及其储钠性能

采用一步固相煅烧工艺制备了碳纳米管原位封装Ni₃S₂纳米颗粒（Ni₃S₂@CNT）,并研究了其作为钠离子电池（SIBs）负极材料的电化学性能. 通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、循环伏安测试、恒流充放电以及交流阻抗等研究了Ni₃S₂@CNT的物相结构、形貌特征以及电化学性能. 电化学测试表明,材料在100 mA·g ^-1电流密度下,放电容量可以达到541.6 mAh·g ^-1,甚至在2000 mA·g ^-1的大电流密度下其放电比容量也可以维持在274.5 mAh·g ^-1. 另外,材料在100 mA·g ^-1电流密度下,经过120周充放电循环后其放电和充电比容量仍然可以保持在374.5 mAh·g ^-1和359.3 mAh·g ^-1,说明其具有良好倍率性能和循环稳定性能. 良好的电化学性能归因于这种独特的碳纳米管原位封装Ni₃S₂纳米颗粒结构. 碳纳米管不但可以提高复合材料的导电性,也可以缓冲Ni₃S₂纳米颗粒在反复充放电过程中产生的体积膨胀效应,明显改善了Ni₃S₂@CNT负极复合材料的电化学性能.     

Nd3+-doped Li3V2(PO4)3 cathode material with high rate capability for Li-ion batteries

A series of Nd3+-doped Li3NdxV2àx(PO4)3(x = 0.00, 0.02, 0.05, 0.08 or 0.1) composites are synthesized by the rheological phase reaction method. The XRD results indicate that Nd3+ions have been successfully merged into a lattice structure. Doped samples show good electrochemical performance in high discharge rate and long cycle. In the potential range of 3.0–4.3 V, Li3Nd0.08V1.92(PO4)3exhibits an initial discharge capacity of 115.8 m Ah/g at 0.2 C and retain 80.86% of capacity retention at 2 C in the 51 st cycle.In addition, Li3Nd0.05V1.95(PO4)3holds at 100.4 m Ah/g after 80 cycles at 0.2 C with a capacity retention of92.4%. Finally, the CV test proves that the potential polarization of Li3Nd0.08V1.92(PO4)3decreased compared with the un-doped one.     

Direct Pyrolysis of Molybdophosphate-based Ionic Salt for One-step Synthesis of N,P Co-doped Carbon/MoO3-x Hybrids with Superior Lithium Storage Performance

N, P co-doped carbon/MoO3-x hybrids(NPC/MoO3-x) were synthesized via one-step pyrolysis of molybdophosphate-based ionic salt precursor. Doped carbon and oxygen vacancies(OVs) were synchronously introduced into the NPC/MoO3-x hybrids without any other redundant procedure. As anodes for lithium-ion batteries, the NPC/MoO3-x hybrids delivered a high initial Coulombic efficiency(ICE) of 81% as well as high charge capacity of 516 mA·h/g after 100 cycles at 1 A/g, indicating the excellent reversibility and rate capability. The enhanced lithium storage performance was attributed to the rational combination of surface engineering and OVs, which is beneficial to the more active sites and fast ionic/electronic transport.     

平板式V_2O_5-MoO_3/TiO_2型SCR催化剂的中低温脱硝和抗中毒性能研究

针对中低温锅炉烟气脱硝技术需求的特点,采用等体积浸渍法,以V_2O_5为活性组分、MoO_3为助剂,制备了高钒高钼含量的V_2O_5-MoO_3/TiO_2型粉末和平板式SCR脱硝催化剂,考察了活性组分和助剂含量对催化剂活性以及抗SO_2和H_2O中毒性能的影响,对反应前后的催化剂进行了微观表征,并针对最优催化剂研究了其在不同烟气工况下催化剂的脱硝性能。结果表明,提升V_2O_5负载量可以有效提高催化剂的脱硝活性;MoO_3助剂的添加也可以提高催化剂的脱硝活性。XPS、XRF、FTIR等表征结果表明,MoO_3的含量会影响催化剂中V~(4+)/V~(5+)的比值,其相对含量的增加有利于催化剂中非化学计量钒物种的形成以及化学吸附氧比例的增加,钼与钒物种间的交互作用是抑制SO_2和H_2O对催化剂的毒化作用的关键。3V_2O_5-10MoO_3/TiO_2平板式催化剂在温度为200℃、空速为3 500 h~(-1)含SO_2和H_2O烟气条件下,经30 d连续反应,脱硝效率稳定维持在82%左右,该催化剂在中低温下具有优异的抗SO_2和H_2O中毒性能以及稳定性。     

基于钴酸锂载体构筑高体积比容量硫基复合材料

锂-硫电池具有高的理论质量/体积能量密度,因而成为最具发展潜力的高比能二次电池体系. 然而,由于硫载体通常采用轻质的碳纳米材料,导致硫基复合材料的振实密度和体积比容量均偏低,制约了电池体积能量密度的提升. 本文尝试采用具有高密度特征的钴酸锂(LiCoO₂)作为硫的载体材料,以构筑高振实密度的硫基复合材料,进而提高硫正极的体积比容量. 研究显示,LiCoO₂对可溶性多硫化物具有较强的吸附作用,能够促进硫的电化学转化,因而提高了硫的活性物质利用率和循环稳定性. 同时,由于具有高的振实密度(1.90 g·cm^-3),S/LiCoO₂复合材料的首周体积比容量高达1750.5 mAh·cm^-3,是常规硫/碳复合材料的2.2倍. 因此,本文利用具有高密度特征的LiCoO₂作为硫载体来提升硫复合材料的体积比容量,有助于实现锂-硫电池的高体积能量密度.     

紫外臭氧处理增强溶液法MoO3薄膜的空穴注入能力

空穴注入层对有机发光二极管的性能有重要的影响,尤其是当器件中的空穴传输材料的最高占据分子轨道能级较深的时候。近年来有许多关于新型的溶液法空穴注入材料的研究。在本文中,我们对溶液法MoO₃薄膜使用了三种不同的处理方法来研究其对空穴注入性能的影响,即：在空气中150 ℃退火;在空气中150 ℃退火再紫外臭氧处理(UVO) 15 min;只进行UVO处理15 min。结果发现当MoO₃薄膜在空气中150 ℃退火后,器件的电流最小,空穴注入能力最差。而当MoO₃薄膜经过UVO处理后,器件的电流显著增大,工作电压大幅下降,器件性能接近于蒸镀的MoO₃薄膜的器件。更惊喜的是,这种改善在MoO₃薄膜仅作UVO处理后也可获得。经定量计算发现MoO₃薄膜经过UVO处理后的空穴注入效率能提高到约0.1。XPS分析表明通过UVO处理后,MoO₃薄膜中Mo⁵⁺成分减少并且薄膜表面的富氧吸附物被有效地消除,使得其化学计量基本与蒸镀的MoO₃薄膜相同。基于这种经UVO处理的溶液法MoO₃作为空穴注入层,器件的最大电流效率可达到48.3 cd∙A⁻¹。     

Synthesis and electrochemical properties of Zn3V3O8 as novel anode material

Zn₃V₃O₈ two-dimensional micro sheets are successfully synthesized by combination of solvothermal method and heat treatment. The Zn₃V₃O₈ has better electrochemical performances after calcinations.     

Synthesis of carbon-coated Li4Ti5O12 and its electrochemical performance as anode material for lithium-ion battery

Carbon-coated Li_4Ti_5O_(12) sample was synthesized by a sol-gel method. The Li_4Ti_5O_(12) powders were obtained by calcinations of the gels at 750, 800, 850,900 ℃ at N_2 atmosphere. The structure, morphology and electrochemical properties of the materials were characterized by SEM, XRD and charge and discharge. The final product sintered at 850 ℃ demonstrates excellent performance with a specific capacity of 163.5 mAh/g after 100 cycles at 1C. Furthermore, the discharge specific capacity of the sample can retain 80 mAh/g at 10C.     

Three‐Dimensional Hierarchical Constructs of MOF‐on‐Reduced Graphene Oxide for Lithium–Sulfur Batteries

A three‐dimensional (3D) hierarchical MOF‐on‐reduced graphene oxide (MOF‐on‐rGO) compartment was successfully synthesized through an in situ reduced and combined process. The unique properties of the MOF‐on‐rGO compartment combining the polarity and porous features of MOFs with the high conductivity of rGO make it an ideal candidate as a sulfur host in lithium–sulfur (Li‐S) batteries. A high initial discharge capacity of 1250 mAh g^?1 at a current density of 0.1 C (1.0 C=1675 mAh g^?1) was reached using the MOF‐on‐rGO based electrode. At the rate of 1.0 C, a high specific capacity of 601 mAh g^?1 was still maintained after 400 discharge–charge cycles, which could be ascribed to the synergistic effect between MOFs and rGO. Both the hierarchical structures of rGO and the polar pore environment of MOF retard the diffusion and migration of soluble polysulfide, contributing to a stable cycling performance. Moreover, the spongy‐layered rGO can buffer the volume expansion and contraction changes, thus supplying stable structures for Li‐S batteries.     

水热合成的MoO3-SnO2催化剂催化氧化二甲醚的性能研究

采用无沉淀剂水热法一步合成了MoO₃-SnO₂复合金属氧化物催化剂,通过调变Mo/Sn物质的量比,考察了催化剂上活性组分MoO_x分散程度对二甲醚（DME）低温氧化生成甲酸甲酯（MF）反应性能的影响。当Mo/Sn=1∶2,反应条件为150℃时,催化剂表现出较好的催化性能,DME转化率为22.0%,MF选择性达到77.6%。实验中采用TEM、XRD、Raman、FT-IR、NH₃-TPD及H₂-TPR等表征对催化剂晶体结构及表面性质进行了分析。结果发现,Mo/Sn物质的量比变化会对催化剂晶体结构产生显著影响,钼氧化物在SnO₂表面形成不同分散程度的MoO_x结构,这种钼氧化物结构的变化进一步影响了催化剂表面的酸性及氧化还原性,是造成催化性能差异的主要原因。     

Lotus-stalk Bi4Ge3O12 as binder-free anode for lithium and sodium ion batteries

The synthesized lotus-stalk Bi₄Ge₃O₁₂ utilized as binder-free anode for LIBs demonstrates excellent cycling performance. The synthesized lotus-stalk Bi₄Ge₃O₁₂ is composed of nanosheets, which is contribute to outstanding lithium storage performance.     

C_(60)与MoO_3混合材料做空穴注入层的单层有机电致发光器件

我们制备研究了基于结构为氧化铟锡(ITO)/C_(60)(1.2nm):MoO_3(0.4nm)/1,3,5-三(1-苯基-1H-苯并咪唑-2-基)苯(TPBi):三(2-苯基吡啶)铱[Ir(ppy)_3](33%,90 nm)/LiF (0.7 nm)/Al (120 nm)的高效绿色磷光单层有机发光二极管(OLED)。分别将C_(60),MoO_3与C_(60):MoO_3混合物作为空穴注入层(HIL)作为对比。TPBi在发光层中起着主体以及电子传输材料的双重作用。在使用电子传输型主体的单层OLED中,空穴注入层性质对于调节电子/空穴注入以获得电荷载流子传输平衡起重要作用。因此,适当调节空穴注入层是实现高效单层OLED的关键因素。由于MoO_3较大的电子亲和能(6.37 eV)会诱导电子从C_(60)的最高占据分子轨道(HOMO)能级转移至MoO_3,从而形成C_(60)阳离子,并使得Mo元素的价态从+6降至+5,C_(60):MoO_3混合就可以较好的调节空穴注入性质。最终实现最大电流效率为35.88 cd·A~(-1)的单层有机发光器件。     

三氧化钼——一种新型有机系钠离子储能器件负极材料

由于锂资源短缺,我们尝试使用三氧化钼作为钠离子储能装置负极材料。通过一种简单的方法合成了三氧化钼,使用XRD、SEM和TEM等测试手段对其物性进行了表征。利用三氧化钼作为有机系钠离子储能器件的负极材料,通过循环伏安和恒流充放电测试探讨了负极材料的储钠机理。以三氧化钼(MoO3)作为负极材料,活性炭(AC)和石墨(graphite)作为正极材料,组装成新型的电化学储能器件,研究了两种器件在1mol/L NaPF6的碳酸丙烯酯(PC)中的电化学性能。两种器件的电压范围分别为0~3.2V和0~3.5V,能量密度最高可分别达到31.6和53 Wh/kg,长循环性能远远优于AC/AC对称电容器。此种储能装置有望成为锂离子电池的一个很好的替代。