石墨烯添加剂与电流密度对铝锂合金阳极氧化膜层耐蚀性能的影响

本文以Al-Li-Cu-Mg合金为研究对象,在混酸电解液体系下进行阳极氧化处理,制备不同电流密度以及石墨烯掺入后的氧化膜。通过SEM、XRD、EDS等分析测试手段分析了各参数下膜层的表面与截面形貌、元素、物相组成等,并通过电化学工作站等仪器分别分析了膜层的耐蚀等性能。研究不同电流大小与石墨烯掺入后对膜层性能的影响机制。结果表明：电流密度的增加会使得材料膜层的厚度先增后减、缺陷增加,耐蚀性能先增后减,阳极氧化膜耐蚀性能最佳电流密度为15 A/dm²。同时石墨烯的掺入会降低膜层耐蚀性,阳极氧化膜腐蚀电流密度为4.898×10^-7 A·cm^-2。     

NiMn2O4尖晶石氧化物阴极的制备及电化学性能研究

高性能阴极材料的开发对推动中温固体氧化物燃料电池（intermediate temperature solid oxide fuel cells, IT-SOFCs）的发展具有重要意义。本文采用溶胶-凝胶法制备了尖晶石型NiMn₂O₄（NMO）电子-离子混合导体材料,并作为IT-SOFCs阴极进行了系统的研究,通过X射线衍射表征确定NMO材料呈稳定的立方相结构,并采用电导弛豫方法对其氧离子传导能力进行了研究。发现NMO具有优秀的氧离子传导能力,为其电化学性能提供了保障。对称电池的电化学阻抗谱测试结果表明,800℃时NMO阴极材料的界面电阻值为0.27 Ω·cm^-2,同时作为阳极支撑型SOFC的阴极材料进行放电时的最大功率密度可以达到864.9 mW·cm^-2。上述结果表明,NiMn₂O₄是一种极具潜力的IT-SOFCs阴极材料。     

锑离子添加剂对低共熔溶剂(DES)电解液液流电池的性能改善研究

非水系氧化还原液流电池（NARFB）的广泛应用受制于其较低的性能。在电解液中加入一些金属离子添加剂是一种可能的解决方案。实验研究了Sb³⁺离子对低共熔溶剂（DES）电解液液流电池电化学性能的影响。结果表明,添加Sb³⁺离子可以强化V（Ⅲ）/V（Ⅱ）氧化还原离子对的电化学反应动力学（最高可达22.6％）过程,钒离子在DES中的扩散系数提高了63.3％,并且电荷转移电阻降低了11.9％。场发射扫描电子显微镜表明,Sb³⁺离子电沉积在石墨毡的表面,对电化学反应起催化作用,从而改善了电化学性能。考虑增强的动力学和降低的活性比表面积之间的平衡,确定了Sb³⁺的最佳浓度为15 mmol·L^-1。此外,当使用含有Sb³⁺的负极电解液液流电池时,液流电池的功率密度提高了31.2%,从含原始电解质的3.08 mW·cm^-2到含15 mmol·L^-1 Sb³⁺离子的4.04 mW·cm^-2。这些结果为改善NARFB的电池性能提供了一个便捷而有前景的方法。     

低温热剥离制备石墨烯及其电化学性能研究

以石墨为原料,采用改进的Hummers法制备了氧化石墨,300℃下热剥离氧化石墨制备得到石墨烯.采用红外光谱、扫描电镜表征了石墨烯的还原程度及形貌结构,运用循环伏安、恒流充放电等测试方法研究了石墨烯的电容性能.结果表明:石墨烯片层之间被充分剥离开来,拥有一定的孔道结构.在1 mol·L-1的硫酸电解液中,石墨烯制备的电极比电容达411 F·g-1.电极组装的电容器,能量密度5.37 W·h·kg-1时,功率密度为604 W·kg-1,循环1000次后比电容保持率为94％.组装的超级电容器电化学性能及循环稳定性能良好.     

氰基丙烯酸乙酯基亲水性导电粘合剂的制备与应用研究

电极粘合剂在储能系统的电极加工中起着重要作用。虽然传统的粘合剂通常需要危险且昂贵的有机溶剂,但越来越多地向更绿色、更便宜的粘合剂发展。该研究通过对氰基丙烯酸乙酯(ECA)与壳聚糖(CST)、聚乙二醇(PEG)、二氧化锰(MnO₂)以及石墨烯浆料(G)进行简单复合,制备一种亲水性导电粘合剂浆料,并将其涂敷在集流体碳布(CC)上制备水系锌离子电极,以ZnSO₄电解质通过三电极体系对电极进行电化学性能表征。研究表明,该粘合剂浆料无需加热烘干,并在滴定30s后接触角为61.2°,具有良好的亲水性。其制备的电极在1mA·cm^-2电流密度下,面积比电容可以达到223.3mF·cm^-2,当电流密度升至5mA·cm^-2时,面积比电容为183.5mF·cm^-2,保持率为82.2%。该研究为开发具有更好可持续性和改进功能的绿色聚合物粘合剂提供一种新的方法。     

Fe_3O_4/石墨烯复合材料的制备及其电化学性能研究

以FeCl_3·6H_2O和FeCl_2·4H_2O为铁源,以Na OH溶液为沉淀剂,选择共沉淀法制备Fe_3O_4∕石墨烯复合物。以Fe⁽²⁺⁾和Fe(2+)和Fe⁽³⁺⁾的浓度作为变量制得5种不同比例的Fe_3O_4/石墨烯纳米复合材料,然后将所得复合材料压制成电极片,组装成超级电容器后进行循环伏安(CV)、恒电流充放电(GCD)、交流阻抗(EIS)测试,探究Fe_3O_4与石墨烯的含量比对复合材料电化学性能的影响。结果表明,当FeCl_3·4H_2O和FeCl_2·4H_2O用量分别为0.456 g和0.665 g,氧化石墨烯用量为150 mg时,所制备复合材料的电化学性能最佳,比电容可达510 F/g。     

离子液体作为电解液添加剂用于高压锂离子电池

合成了功能化离子液体1-丁基-3-甲基咪唑双（三氟甲磺酰）亚胺盐（BMIMTFSI）作为高压锂离子电池电解液添加剂,用于抑制有机溶剂的氧化,以提高碳酸酯类电解液的耐高压性。分别采用充放电测试、电化学交流阻抗（EIS）、循环伏安法（CV）和扫描电子显微镜（SEM）等研究了LiNi_0.5Mn_1.5O₄/Li电池的电化学行为和LiNi_0.5Mn_1.5O₄材料表面形貌。结果表明,当在电解液中添加20% （体积分数）BMIMTFSI时,LiNi_0.5Mn_1.5O₄/Li电池在室温、0.2C下的最高放电比容量是126.81 mA·h·g^-1,5C下的放电比容量为109.36 mA·h·g^-1,比在1 mol·L^-1 LiPF₆-EC/DMC电解液中的放电比容量提高了91.7%;且该电池在0.2C下循环50圈后的放电比容量保持率在95%左右,比用碳酸酯类电解液提高了近10%。SEM结果表明,在碳酸酯类电解液中加入BMIMTFSI后,LiNi_0.5Mn_1.5O₄电极表面附着了一层均匀且致密的固态电解质界面（SEI）膜。     

Mo2N量子点@N-掺杂石墨烯复合材料的制备及储锂性能

为改善钼氮化物的电化学储锂性能，以钼酸铵、六次甲基四胺及氧化石墨烯（GO）为原料，通过水热、冷冻干燥及在H₂/N₂混合气中热处理，制备了Mo₂N量子点@氮掺杂石墨烯复合材料（Mo₂N-QDs@Ngs），并探究了GO复合量对电化学储锂性能的影响。透射电子显微镜（TEM）测试结果表明：制备的Mo₂N量子点尺寸约为2~5 nm，Mo₂N量子点均匀地分布在氮掺杂石墨烯的表面。电化学测试结果表明：当GO复合量为30%时（Mo₂N-QDs@Ngs-30），制备的复合材料具有最佳的电化学储锂性能，其在0.1 A·g^-1的电流密度下具有699 mA·h·g^-1的比容量，在2 A·g^-1下仍具有286 mA·h·g^-1的比容量。     

插层硫酸催化氧化石墨制备高比电容石墨烯

通过插层硫酸催化氧化石墨脱水制备高比电容石墨烯。低温加热条件下,经过氧化石墨中嵌入的硫酸催化作用,氧化石墨会迅速脱水和脱去羧基而剥离和还原生成功能化石墨烯。这种制备石墨烯的方法,可简单快速地制备大量功能化石墨烯材料。这种表面功能化的石墨烯具有较高的电化学容量,在1mol/L的 H₂SO₄溶液中,以0.5A/g的电流密度充放电时,电化学容量高达226F/g。     

MoCo@NF电极材料的制备及析氧性能研究

为研究水热法制备泡沫镍负载钼钴析氧电极材料的影响因素,采用正交实验方法制备了一系列析氧电极材料,结合电化学性能分析得出降低析氧过电位的最佳条件。通过SEM、EDS及电化学性能研究了最佳条件下制备的电极材料,研究表明,泡沫镍表面负载了呈现出花朵状的钼钴氧化物,表现出较好的析氧性能,其电极电流密度在100m A·cm^-2的过电位为311m V,Tafel斜率为72m V·dec^-1,双电层电容Cdl为20.85m F·cm^-2,1h内电流密度保持率达95.71%。     

Synthesis of a pyrene-functionalized hyperbranched polyethylene ternary copolymer for efficient graphite exfoliation in chloroform and formation of ethylene-vinyl acetate/graphene nanocomposites

A strategy for preparing ethylene-vinyl acetate (EVA)/graphene nanocomposites from liquid-phase exfoliated graphene has been explored with the use of a pyrene-functionalized hyperbranched polyethylene (HBPE) ternary copolymer, HBPE@Py@PMA, as stabilizer for graphite exfoliation. The HBPE@Py@PMA was synthesized by combining the Pd-diimine-catalyzed chain walking ternary ethylene copolymerization and atomic transfer radical polymerization techniques and has been confirmed to possess a HBPE core simultaneously bearing pyrene terminal groups and polymethacrylate side chains. As stabilizer, it is found to effectively promote graphite exfoliation in CHCl₃ to render high-quality few-layer graphene with an efficiency as high as 43%. Meanwhile, it can be steadily adsorbed on the exfoliated graphene surface to concurrently render functionalized graphene well dispersible in EVA matrix with strong interfacial interactions. This allows us to obtain EVA/graphene nanocomposites from resulting graphene dispersion through simple solution mixing process. By adding only 0.5 wt% of graphene, the dielectric constant of resulting composite increases by 55% compared to pure EVA, with a dielectric loss only 0.012. The role mechanism of the HBPE@Py@PMA for promoting graphite exfoliation in CHCl₃ and the formation of EVA/graphene nanocomposites from the resulting graphene has been proposed.     

Microwave assisted exfoliation and reduction of graphite oxide for ultracapacitors

We report a simple yet versatile method to simultaneously achieve the exfoliation and reduction of graphite oxide. By treating graphite oxide powders in a commercial microwave oven, reduced graphite oxide materials could be readily obtained within 1 min. Extensive characterizations showed that the as-prepared materials consisted of crumpled, few-layer thick and electronically conductive graphitic sheets. Using the microwave exfoliated graphite oxide as electrode material in an ultracapacitor cell, specific capacitance values as high as 191 F/g have been demonstrated with KOH electrolyte.     

Application of Film-forming Additives for Ionic Liquid Based Electrolyte

N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide was synthesized for the application in ionic liquid based electrolytes in lithium ion battery, 10% vinylene carbonate (VC) and 10% 1,3-propane sultone (PS) were added to the electrolyte system respectively as additives to improve the property of solid electrolyte interface and cyclic performance. The results of cyclic voltammetry showed that homogenous and compact solid electrolyte interface film formed on graphite electrode which was detected by observing the morphology of cycled graphite anode. Charging and discharging performance of LiFePO4/Li half cell was tested in the electrolyte with or without additives. The initial specific discharging capacities were increased to 129.4 and 123.0 mA×h/g by the addition of VC and PS, respectively, compared with that of additive-free electrolyte. The discharging retentions were 88.9% and 84.6% in electrolyte containing VC and PS after 10 cycles.     

绝缘衬底上化学气相沉积法生长石墨烯材料

利用化学气相沉积法,在Si衬底、蓝宝石衬底和SiC衬底上生长石墨烯材料,研究石墨烯的表面形貌、缺陷、晶体质量和电学特性。原子力显微镜、光学显微镜和拉曼光谱测试表明,Si₃N₄覆盖层可以有效抑制3C-SiC缓冲层的形成;低温生长有利于保持材料表面的平整度,高温生长有利于提高材料的晶体质量。5.08 cm蓝宝石衬底上石墨烯材料,室温下非接触Hall测试迁移超过1000 cm²·V^-1·s^-1,方块电阻不均匀性为2.6%。相对于Si衬底和蓝宝石衬底,SiC衬底上生长石墨烯材料的表面形态学更好,缺陷更低,晶体质量和电学特性更好,迁移率最高为4900 cm²·V^-1·s^-1。     

原位构建富氟SEI的凝胶电解质用于金属锂二次电池

以六氟磷酸锂（LiPF₆）为四氢呋喃的聚合引发剂制备凝胶电解质,同时作为氟源在金属锂负极表面原位构建富含LiF的固态电解质界面层（solid electrolyte interface,SEI）来抑制锂枝晶的生长以及金属锂/电解液之间的副反应。所制备的凝胶电解质具有较高的室温离子电导率（1.33 mS·cm^-1）和较宽的电化学稳定窗口（4.5 V）。原位聚合方式组装金属锂对称电池循环后,锂负极表面没有明显的锂枝晶和被损毁的形貌出现;XPS结果表明锂负极表面生成了富含LiF的SEI。组装的LiFePO₄全电池在1 C的电流密度下,稳定循环400周后仍保持118.7 mAh·g^-1的放电比容量。得益于四氢呋喃在开环聚合反应过程中,促进了LiPF₆分解反应平衡的正向移动,在锂负极表面形成稳定的富含LiF的SEI,能够抑制锂枝晶的生长并防止其被持续性的腐蚀破坏。     

Preparation and electrochemical properties of NiMn2O4 spinel oxide cathode

Developing high-performance cathode materials is of great significance to promote the development of intermediate temperature solid oxide fuel cells (IT-SOFCs). In this paper, the spinel-type NiMn₂O₄ (NMO) electron-ion mixed conductor material was prepared by the sol-gel method, and it was systematically studied as the cathode of IT-SOFCs. It is found that NMO material has stable cubic phase structure by using X-ray diffraction (XRD) and the conductivity of oxygen ions is studied by the technique of electrical conductivity relaxation (ECR). It shows that NMO has excellent oxygen-ion conductivity, which provides guarantee for its electrochemical performance. Impedance spectroscopy measurements of a symmetrical cell shows a low interface impedance, which is only 0.27 Ω·cm^-2 at 800℃. At the same time, an anode-supported SOFC with NMO cathode presents a maximum power density of 864.9 mW·cm^-2 at 800℃. The above results demonstrate that NiMn₂O₄ is a potential cathode material for IT-SOFCs.     

Accelerating rate calorimetry studies of the reactions between ionic liquids and charged lithium ion battery electrode materials

Using accelerating rate calorimetry (ARC), the reactivity between six ionic liquids (with and without added LiPF₆) and charged electrode materials is compared to the reactivity of standard carbonate-based solvents and electrolytes with the same electrode materials. The charged electrode materials used were Li₁Si, Li₇Ti₄O₁₂ and Li_0.45CoO₂. The experiments showed that not all ionic liquids are safer than conventional electrolytes/solvents. Of the six ionic liquids tested, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI) shows the worst safety properties, and is much worse than conventional electrolyte. 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI) and 1-propyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide (Py13-FSI) show similar reactivity to carbonate-based electrolyte. The three ionic liquids 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide (BMMI-TFSI), 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide (Pp14-TFSI) and N-trimethyl-N-butylammonium bis(trifluoromethanesulfonyl)imide (TMBA-TFSI) show similar reactivity and are much safer than the conventional carbonate-based electrolyte. A comparison of the reactivity of ionic liquids with common anions and cations shows that ionic liquids with TFSI⁻ are safer than those with FSI⁻, and liquids with EMI⁺ are worse than those with BMMI⁺, Py13⁺, Pp14⁺ and TMBA⁺.