介孔四氧化三锰纳米棒的快速低成本制备与电化学性能

仅以乙醇和四水合醋酸锰为原料, 快速低成本地合成了介孔四氧化三锰纳米棒, 并将其应用于锂离子电池负极材料。通过X 射线衍射、热重分析仪、扫描电子显微镜、透射电子显微镜和比表面积仪等分析手段对四氧化三锰样品进行了表征。实验结果表明: 介孔四氧化三锰纳米棒的平均直径约为150 nm, 孔的尺寸范围为6~20 nm, BET比表面积高达37.3 m²/g。同时, 介孔四氧化三锰纳米棒负极材料在141 mA/g的电流密度下循环100次后可逆充放电容量为676.1和662.4 mAh/g, 而且其在不同的电流密度下继续循环80次后可逆放电容量高达850 mAh/g, 体现出了较高的容量、好的循环稳定性能和倍率性能。     

溶胶-凝胶法合成锂离子电池正极材料LiMn_2O_4

以醋酸锰、硝酸锂为原料,采用乙二胺四乙酸-柠檬酸(EDTA-CA)络合法,制备了正尖晶石型LiMn2O4超细粉末晶体。应用TG-DSC,XRD,CV及恒流充放电测试等手段对前躯体及LiMn2O4粉体进行性能表征,确定了其最终的合成温度为600℃。常温下,组装成半电池,初始放电容量为120.2mAh/g,循环50次后容量保持在70%左右。     

锰氧化物的结构分析及其在能源与环境中的典型应用EI北大核心CSCD

锰氧化物作为最常见的过渡金属氧化物之一,是一种极具潜力的材料,可通过改变其晶型、形貌、比表面积和氧空位数量等调节催化活性、吸附能力、稳定性等性能。调控MnO_(X)的晶体结构及形貌以提高其性能,一直是国内外学者极为关注的问题。本文分析了不同晶型二氧化锰(α,β,γ,δ,λ)的结构特点及其与催化/吸附性能之间的构效关系,系统总结了不同形貌MnO_(X)(纳米棒、纳米片、纳米花、纳米球)的制备方法及结构特点,并介绍了锰氧化物近年来在能源(生物质催化转化、电化学)及环境治理(气体污染物分解、重金属吸附、有机污染物降解)中的典型应用。最后,对锰氧化物存在作用机制复杂、稳定性较差等问题进行了分析。尽管锰氧化物在研究过程中还存在问题,但其作为一种重要的金属氧化物,未来在环境、能源等领域中的应用前景十分广阔。     

Enhanced zinc storage performance of mixed valent manganese oxide for flexible coaxial fiber zinc-ion battery by limited reduction control

While manganese-based cathodes have been intensively studied for zinc-ion batteries (ZIBs),the limited rate capability and cycle life have always been a difficult problem to be solved.Here,we report a mixed valent manganese oxide (MnOx) cathode with superior electrochemical performance,which exhibits a high specific capacity of 450 mA h/g at 0.2 C and a satisfactory specific capacity of 158.3 mA h/g at a high rate of 5 C.The mixed cathode system reduces the charge transfer resistance,and show good surface stability and adsorption properties,so it is beneficial for the storage of Zn2+.Meanwhile,coaxial fiber ZIBs (CFZIBs) with splendid flexibility are assembled utilizing the elaborately prepared cathode material.The CFZIBs achieve a reversible capacity of 255.8 mA h/g and the capacity retention rate is as high as 80 ％ after 1000 bending deformations.This study provides new opportunities for designing ZIBs with high performance and high flexibility.     

Bi和F复合掺杂对LiMn2O4结构及电化学性能的影响

采用固相法合成LiMn2-xBixO4-yFy(x=0,0.03;y=0,0.05,0.1),通过X-射线衍射、扫描电子显微镜、恒电流充放电及循环伏安等技术分析检测合成材料的结构、形貌及电化学性能。结果表明:合成的LiMn2-xBixO4-yFy均为尖晶石结构,无杂相,颗粒表面光滑,大小均匀。常温下以0.2C倍率循环30次,LiMn1.97Bi0.03O3.95F0.05容量保持率为90.88%,远高于未改性LiMn2O4的86.51%,常温及55℃下以1 C倍率循环100次,LiMn1.97Bi0.03O3.95F0.05容量保持率分别为91.81%和83.69%,高于未改性的78.65%和71.82%。Bi和F复合掺杂提高了材料的稳定性和循环性能,尤其是高温循环性能。     

锂离子二次电池正极材料氧化锰锂的研究进展

综述了最近几年对于锂离子二次电池正极材料氧化锰锂的研究。研究的氧化锰锂材料主要有尖晶石结构的ＬｉＭＮ２Ｏ４、Ｌｉ４Ｍｎ５Ｏ９和Ｌｉ４Ｍｎ５Ｏ１２以及层状结构的ＬｉＭｎＯ２。对于ＬｉＭＮ２Ｏ４,通过引入适当的杂原子和采用新的溶胶－凝胶法制备复相 可以有效地克服Ｊａｈｎ－Ｔｅｌｌｅｒ效应所造成的容量衰减现象。Ｌｉ４Ｍｎ５Ｏ９display structure     

层状二氧化锰/苯胺-邻甲氧基苯胺共聚物复合材料的制备与性能研究

采用软化学合成法合成出基面间距为0.70nm的层状二氧化锰(bir-MnO2),并利用表面吸附技术制备了层状二氧化锰/苯胺-邻甲氧基苯胺共聚物复合材料(bir-MnO2/P(An-co-oAs)),借助FTIR、XRD、SEM、TGA、四探针和充放电循环实验等测试手段对样品的结构与性能进行表征.结果表明,P(An-co-oAs)的引入,对复合材料中bir-MnO2的层状结构破坏较小,P(An-co-oAs)通过氢键和静电作用吸附在bir-MnO2的表面.与bir-MnO2相比,复合材料的电导率提高2个数量级.首次放电比容量由bir-MnO2的188mAh/g提高到复合材料的202mAh/g.     

锂离子电池正极材料的研究进展

综述了近年来发展起来的一些锂离子电池正极材料 ,主要包括嵌锂的层状LixMO2 结构和尖晶石型LixM2 O4 结构的过渡金属氧化物 (M =Co、Ni、Mn、Cr等 )。重点介绍了锂钴氧化物、锂镍氧化物、锂锰氧化物的性能、制备、结构以及改性方法等 ,并对纳米电极材料和其它正极材料的发展情况作了简介     

Degradation of high-voltage cathodes for advanced lithium-ion batteries – differential capacity study on differently balanced cells

The degradation of LiNi_0.5Mn_1.5O₄ (LNMO) cathodes were investigated using different cell designs (half cells, full cells cathode-limited, anode-limited and cathode-limited with pre-charge). Half cells based on Li/LNMO show long-cycle stability due to the unlimited source of electrochemically available lithium. Full-cell configurations with Li₄Ti₅O₁₂/LNMO are limited in their cycling performance and durability. Differential capacity studies during continuous cycling reveal a systematic intensity change of the Ni^II/III and Ni^III/IV redox peaks as a function of the amount of electrochemically available lithium. As a mechanism, it could be clearly stated that the consumption of electrochemically available lithium determines the cycle stability. The decomposition of the active material itself (e.g. loss of Ni and Mn) is not crucial for the capacity loss. Thus, full cells with a pre-charged anode have the best cycling performance because of its high lithium content.     

锂锰复合物在3V二次锂电池中的应用研究

利用固相反应法由热处理过的电解二氧化锰与LiOH·H2O的混合物制备锂锰复合物(CDMO),采用热分析研究了温度对γ-β-MnO2与LiOH·H2O混合物发生固相反应的影响,采用X射线衍射对二氧化锰和CDMO的晶体结构进行了表征,并将CDMO制成正极组装电池对其进行了恒电流充放电性能测试.研究结果表明,用该方法制备的CDMO有较好的充放电循环性能.     

新型线性三核锰（Ⅱ）配合物的最小及最佳纳米颗粒结构表征及计算

从新型线性三核锰（Ⅱ）配合物的晶体结构入手,对配合物的最小纳米颗粒提出假设,并通过配合物不同粒径尺度的晶胞数、原子数及表面原子数占总原子数的比例进行计算分析,探讨其相关规律,确定其最佳纳米尺度为100nm,为纳米颗粒的制备提供一定理论依据。     

Structure, magnetic and thermal properties of Gd2MnTiO6

A new perovskite compound Gd₂MnTiO₆ was synthesized and its crystal structure, magnetic and thermal properties have been investigated. The XRD patterns were refined by the Rietveld method and the refined lattice parameters with the monoclinic space group P2₁/n (No. 14) were a=0.5398 (2), b=0.5704 (2), c=0.7767 (2) nm and β=89.68 (2)°. The antiferromagnetic behavior was observed below 16.0 K and λ-type heat capacity was measured near this temperature.     

Mn和Fe掺杂对尖晶石氧化物Co2MnO4结构和磁性的影响

以金属盐及柠檬酸为原料, 采用溶胶-凝胶法制备了尖晶石氧化物Co_2-xMn_1+xO₄和Co_2-xFe_xMnO₄系列, 通过XRD、FT-IR及PPMS等手段研究了Co₂MnO₄及系列掺杂样品的成相、结构、磁性等特征。结果表明, Co_2-xMn_1+xO₄系列在x<0.6时, 呈单相立方结构, 晶格常数和磁性随着Mn掺杂量的增加而增大, x≥0.6时逐渐向四方结构转化, 磁性下降, 并呈现磁化强度不易饱和的特征; Co_2-xFe_xMnO₄系列样品在x<1.75成分范围内均可保持立方结构, 且晶格常数和磁性都随着x增大而提高。这些变化主要是由于掺杂原子尺度及磁矩均大于原有元素, 掺杂后样品内部的磁性相互作用有所增强。     

Synthesis and Characterization of Mesoporous Manganese Oxides

Mesoporous manganese oxide (MPMO) K_0.216MnO₂ 1.26H₂O was synthesized by reduction of KMnO₄ with maleic acid. Its composition and structure were analyzed and characterized by inductive coupled plasma atomic emission spectrometry (ICP-AES), titration, X-ray powder diffractometry (XRD), thermogravimetry (TG)-differential thermoanalysis (DTA). The morphology and pore structure of the MPMO material were accomplished by means of high-resolution transmission electron microscopy (HRTEM) and N₂ sorptometry and transmission electron microscopy (TEM). The results show that MPMO is a pseudocrystalline material with complex network pore structure; its BET surface area is 261.6 m²/g and pore diameter distribution is approximately in the range of 2–10 nm. The MPMO material turns into -MnO₂ when the calcinating temperature rises to 400°C.     

不同晶相MnS制备及光解H2S制氢性能研究

采用溶剂热法成功制备了具有立方结构的α-MnS和六方结构的γ-MnS。通过X射线衍射(XRD), 扫描电子显微镜(SEM), 透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)、选区电子衍射(SAED)和紫外-可见吸收光谱(UV-Vis), 对样品的物相组成、显微形貌、光学性质进行了研究, 并对不同晶相MnS在可见光(λ > 420 nm)和全光谱下光解H₂S制氢性能进行了研究。结果表明: α, γ-MnS在可见光下都具有光解H₂S制氢活性, 且相比于热力学稳定相的α-MnS (4.24 μmol/(g·h)), 亚稳态的γ-MnS (23.38 μmol/(g·h))具有更好的催化性能。相对于可见光, α, γ-MnS在全光谱下的产氢速率明显提高, 其中γ-MnS在全光谱下具有最大的光解H₂S制氢活性, 其产氢速率可达 2272.69 μmol/(g·h)。值得注意的是, 在6 h的光催化测试过程中, α, γ-MnS都展示较好的抗光腐蚀能力和光催化稳定性。此外, 对α, γ-MnS光催化分解H₂S制氢机理进行了分析, 通过对α, γ-MnS光电化学性质的研究, 对其光催化活性存在差异的原因进行了探讨。     

Hydrothermal stability of some manganese oxides

Hydrothermal phase reaction studies in the systemsβ-MnO₂-H₂O,γ-Mn₂O₃H₂O andγ-MnO₂-H₂O have been carried out. Based on the experimental data and the reported phase diagrams in Mn₂O₃-H₂O and MnO-H₂O systems, hydrothermal stability temperature of some of the manganese oxide minerals has been defined.     

锂空气电池用碳纳米管/钴锰氧化物复合电极材料的制备及电化学性能

采用沉淀法合成了不同钴锰含量的碳纳米管(CNTs)/钴锰氧化物纳米复合材料. 利用XRD、SEM、TEM、BET和FT-IR等方法对材料进行了表征, 考察了不同复合材料对锂空气电池放电及充电过程的影响, 同时对循环性能进行了研究. 结果表明: 钴锰比例为4:0与0:4时, 产物为CNTs/Co₃O₄与CNTs/Mn₃O₄, 钴锰比例为3:1、2:2、1:3时, 产物为CNTs/(Co, Mn)(Co, Mn)₂O₄。产物具有良好的分散性能, 氧化物负载在碳管表面, 其中CNTs/Mn₃O₄的分散性能最好。随着锰含量的增加, 电池的放电性能提高, CNTs/Mn₃O₄的放电电压达到2.92 V。随着钴含量的增加, 电池的充电性能提高, 充电电压最低为3.80 V。钴锰比为3:1时的产物充放电过电势(△V)仅为1.05 V, 5次循环后依然保持着良好的放电性能。