简化的溶胶凝胶法合成LiMn2-xLaxO4及电性能研究

采用以水溶液作为反应介质的简化的溶胶凝胶法制备了LiMn2O4和稀土La掺杂的LiMn1.98La0.02O4粉体材料, 此方法工艺简单, 容易控制, 制备周期短. 利用XRD, SEM对材料粉体进行结构形态表征, 并以合成的材料为正极活性材料测试其充放电性能、循环伏安性能、 电化学阻抗谱性能. 实验结果表明: 材料LiMn2O4和LiMn1.98La0.02O4具有较好的尖晶石结构, 且颗粒分布均匀, 掺杂La的材料循环性能有较大改善. 以LiMn2O4为正极活性物质的扣式电池首次放电比容量129.38 mAh · g-1, 循环20次后容量保持在94%, 以LiMn1.98La0.02O4为正极活性物质的扣式电池首次放电比容量106.77 mAh · g-1, 循环20此后容量保持在96.2%.     

锂硫二次电池硫-碳纳米管正极的合成和性能

由单质硫与碳纳米管合成一种新型含碳复合材料.XRD、SEM、BET比表面和孔径分布表征观察硫-碳纳米管复合材料,循环伏安法和电池充放电测试材料的电化学性能.结果表明:以硫-碳纳米管作正极组装的2016型扣式电池有较好的电化学性能,其初始放电比容量达680mAh/g(室温),30次循环放电比容量仍稳定在500mAh/g.     

无机聚合物正极材料聚三硫代磷氮烯的制备与表征

合成了无机化合物聚三硫代磷氮烯[NPS3]n,借助红外光谱与元素分析测试确定了聚合物的重复单元结构;并通过比表面积分析、粒度测试和扫描电子显微镜观察了无机聚合物材料的微观形貌;热重分析测试表明材料在300℃以下能够稳定使用;循环伏安实验发现,作为锂二次电池正极材料使用,聚三硫代磷氮烯的电化学还原反应在2.25 V(versus Li/Li+)发生,其可逆的电化学氧化反应在2.51 V(versus Li/Li+)进行;充放电测试显示这种无机材料具有745.2 mAh.g-1的首次放电容量,与理论值(759.0 mAh.g-1)十分接近,经过60次充放电循环后放电容量保持在708.8 mAh.g-1,容量保持率95.1%,循环性能优秀.     

AlF3包覆对Li1.2Mn0.534Ni0.133Co0.133O2正极材料电化学性能的影响

通过共沉淀法制备锂离子电池富锂锰基正极材料Li1.2Mn0.534Ni0.133Co0.133O2,并对其进行AlF3包覆。实验结果表明,通过AlF3包覆,材料的电化学性能得到明显提高。在0.2C下,包覆前材料的首次放电比容量为253 mAh.g-1,首次充放电效率仅为88.8%。经过AlF3包覆,材料的首次放电比容量提高到294 mAh.g-1,首次充放电效率高达96.4%。同样,在1.0C下循环50次,未包覆材料的放电比容量由225 mAh.g-1降到185 mAh.g-1,容量保持率仅为82.2%。经过AlF3包覆,材料的放电比容量由230mAh.g-1仅降为222 mAh.g-1,容量保持率高达96.5%。     

高性能锂-硫电池用复合正极的构造与粘结剂

采用球磨混合及热处理方法制备了含有多壁碳纳米管(MCNTs)的硫基复合正极材料,利用X射线衍射(XRD)和扫描电子显微镜(SEM)测定材料的结构和形貌,较系统地研究了MCNTs含量和粘结剂种类对硫基复合正极容量、循环稳定性和自放电行为等的影响.结果表明:MCNTs的合适含量为5%-8%(w,质量分数),以水性粘结剂环糊精制备的硫基复合正极电化学性能最佳.锂-硫电池在常温和半充电状态下放置30天几乎没有自放电;当电流倍率为0.1C时,β-环糊精为粘结剂的正极初始充电容量为687.7mAh.g-1,100次循环以后可逆容量为623.8mAh.g-1,容量保持率达90.7%.     

锂离子电池正极材料LiLa_x Mn_(2-x)O_4的高温固相合成及其电化学性能

以LiAc,MnAc2和LaCl3为原料,通过高温固相两段烧结合成法制备了4种LiLaxMn2-xO4(Fx,x=0,0.02,0.04,0.06),其结构和形貌经XRD和SEM表征。结果表明,LiLa0.02Mn1.98O4(即F0.02)为纯尖晶石结构,表面形貌为球形。采用活性炭为导电剂制备了Fx的锂离子电池正极材料(Ex),并用循环伏安法研究了Ex的电化学性能。结果表明,E0.02在0.1 C倍率充放电时的首次放电容量为75 mAh·g-1;0.5 C倍率循环充放电时,放电比容量为79 mAh·g-1;经过20次0.2 C倍率循环充放电时,容量保持在80 mAh·g-1。     

LiNi0.49Mn1.49Y0.02O4的合成及其电化学性能研究

应用柠檬酸辅助溶胶-凝胶法.合成了Y3+掺杂的尖晶石LiNi0.49Mn1.49Y0.02O4材料.XRD、循环伏安、恒流充放电和交流阻抗测试结果表明,Y3+的掺杂能提高LiNi0.5Mn1.5O4的倍率和循环性能.在电压区间3.5～4.9V,1C倍率下,其初始放电比容量为114.9 mAh.g-1,100次循环后放电比容量仍可达113.0 mAh.g-1,容量保持率为98.3%.掺杂Y3+能减小材料界面阻抗.     

锂离子电池正极材料Li_(1.2)Mn_(0.54-x)Ni_(0.13)Co_(0.13)Zr_xO_2的制备及电化学性能

为了改善富锂锰基正极材料Li1.2Mn0.54Ni0.13Co0.13O2的循环性能,采用燃烧法合成了正极材料Li1.2Mn0.54-xNi0.13Co0.13ZrxO2(x=0.00,0.01,0.02,0.03,0.06).通过X射线衍射(XRD)和扫描电镜(SEM)对其结构与形貌进行了表征,利用恒电流充放电测试,循环伏安(CV)及电化学交流阻抗谱(EIS)技术对其电化学性能进行测试.结果表明,Li1.2Mn0.54-xNi0.13Co0.13ZrxO2(x=0.00,0.01,0.02,0.03,0.06)正极材料均具有α-NaFeO2型层状结构;在室温,2.0-4.8 V电压范围,以0.1C和1.0C(充放电电流以1.0C=180 mA·g-1计算)倍率充放电进行测试,样品Li1.2Mn0.52Ni0.13Co0.13Zr0.02O2的首次放电比容量分别为280.3和206.4 mAh·g-1.其中,在1.0C倍率下,100次循环后容量保持率由原来的73.2%提高到88.9%;以5.0C倍率充放电进行测试,经50次循环后,掺杂正极材料的放电比容量为76.5 mAh·g-1,而未掺杂材料仅有15.0 mAh·g-1.在50、25和-10°C,2.0C倍率条件下,掺杂正极材料的电化学性能均得到有效改善,其中,在-10°C经过50次循环后正极材料Li1.2Mn0.52Ni0.13Co0.13Zr0.02O2比未掺杂的正极材料相比,其放电比容量提高了61.1%.     

锂离子电池正极材料LiV3-xAlxO8的水热合成与性能

采用水热法制备了Al掺杂的锂二次电池正极材料LiV3-xAlxO8,并用X射线衍射和扫描电镜对材料的晶体结构和形貌进行了表征.以50 mA·g-1进行恒流充放电测试,结果表明Al掺杂能够明显改善材料的电化学性能.在掺杂改性的LiV3-xAlxO8材料中,LiV2.93Al0.07O8的初始容量最高,达到325 mAh·g-1.当掺杂量为x=0.04时,材料的循环性能最佳.LiV2.96Al0.04O8经20次循环后仍保持179 mAh·g-1的比容量,且充放电效率始终维持在98%左右.     

WO_3纳米棒/石墨烯复合材料的制备及电化学储锂性能

以氯化钨和氧化石墨烯(GO)为原料,乙醇为溶剂,一步合成了WO3纳米棒/石墨烯纳米复合材料(WO3/RGO).将WO3/RGO纳米复合材料用于锂离子电池负极,并通过充放电测试、循环伏安(CV)和电化学阻抗谱(EIS)技术综合考察了该材料的储锂性能.结果显示,在0.1C(1C=638 mA?g-1)倍率下,复合物的首次放电比容量达到761.4 mAh?g-1,100次循环后可逆容量仍保持在635 mAh?g-1,保持率为83.4%.即使在5C倍率下容量仍高达460 mAh?g-1.由此说明,WO3/RGO纳米复合物具有优异的循环稳定性及倍率性能,可望用于高性能锂离子电池.     

Self-Supported ZIF-Derived Co3O4 Nanoparticles-Decorated Porous N-Doped Carbon Fibers as Oxygen Reduction Catalyst

Oxygen reduction is a significant cathodic reaction in the state-of-art clean energy devices such as fuel cell and metal–oxygen battery. Here, ZIF-incorporated hybrid polymeric fibres have been fabricated by using a dual-phase electrospinning method. These are then transformed into Co₃O₄-nanoparticle-decorated porous N-doped carbon fibres (ZIF-Co₃O₄/NCF) through multi-step annealing treatment. The resultant ZIF-Co₃O₄/NCF is interweaved into a self-supported film and can be used as a bi-functional catalyst for catalysing oxygen reduction in both aqueous and non-aqueous electrolytes. Electrochemical tests demonstrate that ZIF-Co₃O₄/NCF displays a high catalytic activity for oxygen reduction with a half-wave potential (E_1/2) of 0.813 V (vs. RHE) and an almost favourable four-electron reduction pathway in alkaline medium. ZIF-Co₃O₄/NCF catalyst only shows 4 mV negative shift of E_1/2 after 5000 continuous CV cycles. In addition, the ZIF-Co₃O₄/NCF can be applied as the cathode catalyst of non-aqueous Li–O₂ battery, exhibiting a remarkable ORR activity in LiPF₆ contained 1,2-dimethoxyethane electrolyte. The excellent electrocatalytic performance of ZIF-Co₃O₄/NCF is probably due to the abundance of active sites of graphitic carbon-wrapped Co₃O₄ nanoparticles, as well as the cross-linked fibrous nitrogen-doped carbon texture.     

氮掺杂碳纤维负载镍钴硒化物的制备及其电催化析氢性能

以静电纺丝制备的纤维为前驱体,通过煅烧、硒化处理等工艺合成了负载双金属硒化物纳米粒子的氮掺杂碳纤维(NCF)材料((Ni,Co)Se2/NCF),并对其进行了一系列相关的表征,研究了其在酸性和碱性条件下的析氢性能.(Ni,Co)Se2纳米粒子被锚定于NCF中,有效地阻止了纳米粒子的聚集,提供了更多的催化活性位点.电催化...     

LiFePO4的软化学合成及锂快离子导体修饰

采用溶剂热法制备正极材料LiFePO_4,采用溶胶凝胶法制备Li_(0.5)La_(0.5)TiO_3(LLTO)粉体,并通过酒精悬浮法对LiFePO_4进行修饰,修饰量为LiFePO_4质量的1%~4%,获得了薄壁蜂窝状自组装结构的LiFePO_4上修饰有球状LLTO纳米颗粒的复合正极材料。通过进行充放电测试、交流阻抗测试及循环伏安测试,研究了不同修饰量对电池的充放电比容量、循环性能及可逆性的影响,发现当LLTO含量为3%(w/w)时,以2C和5C倍率放电相对于没有修饰LLTO的LiFePO_4的比容量分别提高29.7%和31.6%,30次循环之后,容量损失率较未改性前减小4.13%,循环伏安曲线上氧化还原峰之间的电位差仅为0.117 V,以3%的LLTO修饰改性的LiFePO_4显著提高了电池的倍率性能、循环性能和低温性能。     

Zr4+离子掺杂对LiFePO4结构及电化学性能的影响

应用固相反应法于惰性气氛下合成掺Zr的L iFePO4正极材料.考察Zr4+掺杂浓度对于目标化合物结构及其电化学性能的影响.XRD,交流阻抗和恒流充放电测试等实验表明,少量的Zr4+掺杂并未影响目标材料产物的结构,反而有利于降低L iFePO4电荷转移反应的阻抗,从而有利于克服该电极过程中的动力学限制.该正极材料表现出优良的倍率放电性能,在0.1C倍率下,L i0.99Zr0.01FePO4的首次放电比容量达135.6mAh.g-1.30次循环后,容量衰减仅3.8%.     

废旧金属网阴极微生物电解池产氢性能及阳极微生物群落结构分析

为寻找质优价廉的析氢催化剂,本研究以废旧金属网为单室微生物电解池(MEC)阴极,在不同外加电压下考察其制氢性能. 同时利用16S rDNA扩增测序技术分析原接种污泥、MFC和MEC阳极微生物的菌落特点. 实验结果表明,随着外加电压的增大,MEC产生的最大电流密度和周期运行时间分别呈现增大和缩短的趋势. 外加0.7 V电压时,废旧金属网阴极MEC的氢气产率和电能回收率分别达到0.330±0.012 m³H₂·m^-3·d^-1和177.0±5.6%,远高于0.5 V时的数值,与0.9 V时相差不大. 废旧金属网阴极MEC的产氢能力可以和Pt/C阴极MEC相媲美,且具有良好的运行稳定性. 16S rDNA扩增测序结果显示培养环境对微生物的富集与淘汰有很大影响. 在外加电场环境中MEC阳极的优势菌落地杆菌属(Geobacter)得到很大程度富集,相对丰度高达79.4%以上.     

Effect of SO2 on Performance of Solid Oxide Fuel Cell Cathodes

Effects of SO₂ in ambient air on the performance and durability of solid oxide fuel cell(SOFC) cathode were evaluated by galvanostatic measurement. Comparison between two cathode materials was made to consider the cathode degradation mechanisms. The degradation performance is associated with a slow decomposition of the La_0.6Sr_0.4Co_0.2Fe_0.8O₃(LSCF) due to the segregation of strontium oxide. Negligible deterioration for (La_0.7Sr_0.3)MnO₃ (LSM) cathode was caused by SO₂ poisoning under a current density of 200 mA/cm². Metal sulphate formation may explain a slight deterioration under increasing high the concentration of SO₂. It was verified that the poisoning mechanism for the two cathode materials resulted from the gradual decomposition of the cathode materials.     

Influence of NaCl on Cathode Performance of Solid Oxide Fuel Cells

Degradation induced by sodium chloride in air was investigated for (La_0.8Sr_0.2)_0.98MnO₃(LSM) and La_0.6Sr_0.4Co_0.2Fe_0.8O₃(LSCF) cathodes in solid oxide fuel cells(SOFC). Cell performance was measured by volatilizing NaCl to be supplied to the cathode at a constant current density of 200 mA/cm² for up to 100 h. At 800 ℃, an exposure of the cathode to 30 mg/L NaCl caused negligible degradation of LSM at least for 100 h. Slight change in the composition of the cathode materials was observed which may imply the gradual degradation of cell performance for the long-term. In addition, cell performance degradation was compared between 700 ℃ and 900 ℃, being poisoned by 30 mg/L NaCl. Degradation was negligible for LSM cathode, while LSCF cathode showed slightly poor tolerance at 700 ℃ due to the decomposition of the cathode material. Further studies should be done to clarify the long-term influence of NaCl on cathode performance.     

阴极冷却反应器电合成乙醛酸

以过饱和草酸水深液为阴极液 ,盐酸溶液为阳极液 ,在阴极冷却电化学反应器内草酸电解合成乙醛酸 .考察了电极温度、电解液温度、电流密度和电极材料对合成乙醛酸的时空产率和电流效率的影响 .结果表明 ,阴极冷却反应器既节省能耗 ,又可使电解过程在较高草酸浓度下进行 ,提高电流效率和时空产率 .用石墨板做阳极 ,铅做阴极 ,电流密度为 4 0 9.4 6A·m-2 ,阴极液流速 μ=1 .0 8m·s-1,电解温度为 2 0℃左右时 ,电解 3 .70h ,可得到质量分数为 3 .52 %的乙醛酸溶液 ,平均时空产率为 0 .0 3 2kg·dm-3·h     

基于微观格点模型模拟PEMFC定向结构催化层

用微观格点模型对质子交换膜燃料电池(PEMFC)定向结构阴极性能进行了模拟,并与随机结构电极进行了对比,研究了催化剂利用率及电池性能的变化.计算了催化层内的传递和电化学反应,研究了质子、氧气及电化学反应速率在电极厚度方向上的分布,并且通过对比氧气浓度、离子电势和电化学反应速率的分布,证明了Pt/C颗粒在电极厚度方向上定向排布有利于提高电池性能.另外,研究了电极厚度对定向结构电极性能的影响,发现与随机结构电极不同,定向结构电极厚度越小,高电流密度下电极性能越好.     

Molecular Bridging Enables Isolated Iron Atoms on Stereoassembled Carbon Framework To Boost Oxygen Reduction for Zinc-Air Batteries

Realizing the synergy between active site regulation and rational structural engineering is essential in the electrocatalysis community but still challenging. Here, a matrix-confined co-pyrolysis strategy based on molecular bridging is demonstrated to realize highly dispersed Fe atoms on stereoassembled carbon framework. Both polyacrylonitrile matrix and organic linker from metal–organic frameworks (MOFs) provide sufficient N-anchoring sites for the generation of Fe−N₄ moieties. A high Fe loading of 2.9 wt.% is readily achieved based on the scalable approach without post-treatment. Owing to the presence of highly exposed Fe−N−C sites and well-tuned pore structures, isolated Fe atoms on porous carbon nanofiber framework (Fe−SA/NCF) exhibits decent oxygen reduction activity and stability in alkaline conditions via a near four-electron path, demonstrating superior performance as air cathode for zinc-air batteries (ZABs) to commercial Pt/C catalyst.