锂离子电池用三维氧化锡/石墨烯水凝胶负极材料

通过溶液水解反应在氧化石墨烯表面引入氧化锡(Sn O2)纳米颗粒,再经过自组装作用形成具有三维结构的氧化锡/石墨烯水凝胶(Sn O2-GH)负极材料。其中三维多孔的石墨烯水凝胶为碳质缓冲基体,Sn O2纳米颗粒为活性物质,其颗粒尺寸为2-3 nm,均匀分布在石墨烯层上,担载量可以达到54%(w,质量分数)。直接将该材料用作锂离子电池负极时,在5000 m A?g~(-1)的大电流密度下循环60次容量稳定在500 m Ah?g~(-1),电流减小到50 m A?g~(-1)循环80次后容量仍高达865 m Ah?g~(-1)。这些优异的循环稳定性和大电流充放电性能主要得益于三维石墨烯水凝胶的疏松、多孔结构和良好的导电性。石墨烯水凝胶能够提高电极比表面积,保证电解液对电极的浸润程度;内部空隙能够为锂离子的传输提供快速通道,缩短离子传输距离和时间。同时丰富的内部空间能够有效避免Sn O2纳米颗粒团聚,缓冲Sn O2巨大体积膨胀,维持电极结构的稳定性,是一种非常适于大电流充放电的锂离子电池负极材料。     

石墨烯复合材料在锂离子电池中的研究进展

石墨烯复合材料因其独特的结构和优异的性质被认为是最有潜力的锂离子电池负极材料之一.石墨烯基复合材料是解决充放电过程中的电极体积变化导致电池的循环性能变差这一问题的有效途径.本文作者综述了多种石墨烯基复合材料作为锂离子电池负极时的电化学性能,并展望了未来的研究方向.     

三维还原氧化石墨烯/聚苯胺复合材料的制备及其超级电容性能

以制备的氧化石墨凝胶和聚苯胺纳米线为原料, 将二者按一定的质量比进行混合超声分散, 再以混合分散液为前驱体采用一步水热法制备得到三维还原氧化石墨烯(RGO)/聚苯胺(PANI) (RGP)复合材料, 采用扫描电镜(SEM), 透射电镜(TEM), X射线衍射(XRD), 傅里叶变换红外(FT-IR)光谱, X射线光电子能谱(XPS)和电化学测试等分析研究了复合材料的形貌、结构和超级电容性能. 结果表明, 复合材料既保持了还原氧化石墨烯的基本形貌, 又能使聚苯胺较好地镶嵌在还原氧化石墨烯的网状结构中; 且当氧化石墨与聚苯胺的质量比为1:1时复合材料在0.5 A·g^-1电流密度下比电容可高达758 F·g^-1, 即使在大电流密度(30 A·g^-1)下其比容量仍高达400 F·g^-1,在1A·g^-1电流密度下循环1000次后比容量保持率为86%, 表现出了良好的倍率性能和循环稳定性, 其超级电容性能远优于单纯的还原氧化石墨烯和聚苯胺, 其优异的超级电容性能可归咎于二者的相互协同作用.     

还原氧化石墨烯/TiO2复合材料在钠离子电池中的电化学性能

二氧化钛(TiO₂)作为有前景的钠离子电池负极材料, 具有良好的循环稳定性, 但由于其导电率较低, 而导致容量和倍率性能不佳限制了其实际应用. 本文采用喷雾干燥技术制备了氧化石墨烯/纳米TiO₂复合材料(GO/TiO₂), 通过热处理获得还原氧化石墨烯/TiO₂复合材料(RGO/TiO₂). 电化学测试结果表明, 还原氧化石墨烯改性的RGO/TiO₂复合材料的电化学性能得到显著提升, RGO含量为4.0%(w)的RGO/TiO₂复合材料在各种电流密度下的可逆容量分别为183.7 mAh·g^-1 (20 mA·g^-1), 153.7 mAh·g^-1 (100 mA·g^-1)和114.4 mAh·g^-1 (600mA·g^-1), 而纯TiO₂的比容量仅为93.6 mAh·g^-1 (20 mA·g^-1), 69.6 mAh·g^-1 (100 mA·g^-1)和26.5 mAh·g^-1 (600mA·g^-1). 4.0%(w) RGO/TiO₂复合材料体现了良好的循环稳定性, 在100 mA·g^-1电流密度下充放电循环350个周期后, 比容量仍然保持146.7 mAh·g^-1. 同等条件下, 纯TiO₂电极比容量只有68.8 mAh·g^-1. RGO包覆改性极大提高了TiO₂在钠离子电池中的电化学嵌钠/脱钠性能. RGO包覆改性技术在改进钠离子电池材料性能中将有很好的应用前景.     

石墨烯及其复合材料在锂离子电池中的应用

石墨烯是一种单原子层厚度的石墨材料,具有独特的二维结构和优异的电学、力学以及热学性能。同时它也是一种具有良好应用前景的锂离子电池电极材料。电极材料的微观结构对其性能有很大影响,利用石墨烯获得具有特殊形貌和微观结构的电极材料,能有效改善材料的各项电化学性能。本文综述了石墨烯及其复合材料在锂离子电池中的应用研究进展。在负极复合材料中,石墨烯不仅可以缓冲材料在充放电过程中的体积效应,还可以形成导电网络提升复合材料的导电性能,提高材料的倍率性能和循环寿命。通过优化复合材料的微观结构,例如夹层结构或石墨烯片层包覆结构,可进一步提高材料的电化学性能。在正极复合材料中,石墨烯形成的连续三维导电网络可有效提高复合材料的电子及离子传输能力。此外,相比于传统导电添加剂,石墨烯导电剂的优势在于能用较少的添加量,达到更加优异的电化学性能。最后对石墨烯复合材料的研究前景进行了展望。     

三维多级孔类石墨烯载三氧化二铁锂离子电池负极材料

采用简单的水解、热处理方法合成三氧化二铁（Fe₂O₃）负载在三维多级孔类石墨烯（3D HPG）上的复合材料. 3D HPG有效的导电网络有利于负载纳米Fe₂O₃,使其呈均匀分散状态,并有效增强纳米复合物的导电率,提高Fe₂O₃利用率,抑制纳米Fe₂O₃的团聚,从而制得稳定、高性能的锂离子电池负极材料. Fe₂O₃-3D HPG电极在50 mA·g^-1电流密度下首次放电容量达1745 mAh·g^-1,50周期放电容量保持于1095 mAh·g^-1.     

三维多孔碳纳米管-还原氧化石墨烯复合气凝胶应用于高性能对称超级电容器

以羟基化的碳纳米管(CNT-OH)和自制的氧化石墨烯(GO)为原料,通过氧化还原自组装的水热合成策略制备了碳纳米管-还原氧化石墨烯(CNTs-rGO)三维气凝胶,并探究了水热温度对三维气凝胶的影响,利用扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)对材料的结构、形貌进行了表征,并对其进行电化学性能测试。其中,在140℃下合成的气凝胶CNTs-rGO展示了最佳的电化学性能,在1 A·g^-1电流密度下的比电容高达294.65 F·g^-1,循环伏安曲线在50 mV·s^-1扫速下的形状仍然近似于矩形,展示了良好的可逆性。将其作为正极和负极材料组装的对称超级电容器在功率密度为249.8 W·kg^-1时的最大能量密度为3.744 Wh·kg^-1,在1 A·g^-1下循环10 000次后,其电容保持率和库仑效率均约为100%。优异的电化学性能主要归因于CNTs-rGO复合材料疏松多孔的三维立体结构,这保证了离子的快速运输,同时CNTs和rGO的交联结构提高了电导率,充分发挥了CNTs和rGO的化学和电学性能。     

三维多孔碳纳米管-还原氧化石墨烯复合气凝胶应用于高性能对称超级电容器

以羟基化的碳纳米管(CNT-OH)和自制的氧化石墨烯(GO)为原料，通过氧化还原自组装的水热合成策略制备了碳纳米管-还原氧化石墨烯(CNTs-rGO)三维气凝胶，并探究了水热温度对三维气凝胶的影响，利用扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)对材料的结构、形貌进行了表征，并对其进行电化学性能测试。其中，在140℃下合成的气凝胶CNTs-rGO展示了最佳的电化学性能，在1 A·g^-1电流密度下的比电容高达294.65 F·g^-1，循环伏安曲线在50 mV·s^-1扫速下的形状仍然近似于矩形，展示了良好的可逆性。将其作为正极和负极材料组装的对称超级电容器在功率密度为249.8 W·kg^-1时的最大能量密度为3.744 Wh·kg^-1，在1 A·g^-1下循环10 000次后，其电容保持率和库仑效率均约为100%。优异的电化学性能主要归因于CNTs-rGO复合材料疏松多孔的三维立体结构，这保证了离子的快速运输，同时CNTs和rGO的交联结构提高了电导率，充分发挥了CNTs和rGO的化学和电学性能。     

碳网封装Fe3O4/还原氧化石墨烯锂离子电池负极材料

通过简单有效的溶剂热法将Fe3 O4颗粒与氧化石墨烯(GO)进行复合,得到Fe3 O4/GO复合材料.将Fe3 O4/GO与葡萄糖进行碾磨.在高温下将GO还原成还原氧化石墨烯(rGO)的同时在Fe3 O4/rGO表面制备网状结构的导电碳层,得到三维网络传输结构C/Fe3 O4/rGO复合材料.由碳网和还原氧化石墨烯组成...     

还原氧化石墨烯/碳纳米管/Co_3O_4三元复合材料的制备与电化学性能

将低温水热反应和低温热处理相结合,制备了含还原氧化石墨烯(RGO)、碳纳米管(CNTs)和Co3O4的三元纳米复合材料RGO-CNTs-Co3O4;利用X射线衍射仪、扫描电子显微镜、透射电子显微镜分析了合成产物的相组成和微观结构,分析了其形成过程;并利用电化学测试装置测定了其作为锂离子电池负极材料的电化学性能.结果表明,在合成反应过程中,氧化石墨烯被还原剂肼还原为石墨烯,同时在石墨烯和CNTs表面生成氢氧化钴;再经低温热处理得到RGO-CNTs-Co3O4三元复合材料.Co3O4纳米颗粒均匀分散在由RGO片层和CNTs组成的三维网络结构中;这种三维网络结构既有利于电子和离子的传输,又能够有效抑制Co3O4在脱嵌锂过程中因体积变化引起的结构破坏.总体而言,合成的新型三元复合材料具有高的比容量以及良好的循环性能与倍率性能.     

基于中空多孔金纳米/石墨烯复合纳米材料的葡萄糖氧化酶直接电化学及其生物传感研究

采用溶液相牺牲模板法制备中空多孔金纳米粒子（HPAuNPs）,并将该材料与还原氧化石墨烯（rGO）复合,用于葡萄糖氧化酶（GOx）在玻碳电极（GCE）表面的有效固定,构建GOx/HPAuNPs/rGO/GCE传感界面。利用扫描和透射电镜、X射线光电子能谱、X射线衍射谱、红外光谱及电化学等方法对材料的形貌与结构,GOx的固定化过程,以及传感器的直接电化学和电催化性能进行表征。结果表明,HPAuNPs和rGO的协同作用能有效促进GOx与电极之间的直接电子转移（DET）。基于GOx/HPAuNPs/rGO/GCE对葡萄糖的良好电催化性能,该方法有效实现了对葡萄糖的高灵敏度检测,其电流响应的线性范围为0.05～7.0 mmol/L,检出限（S/N=3）为16μmol/L。该传感器具有良好的选择性、重现性及稳定性,对实际样品血清中血糖的测定结果令人满意,回收率为98.0%～103%,相对标准偏差不大于5.0%。     

In-situ Grown SnO2 Nanospheres on Reduced GO Nanosheets as Advanced Anodes for Lithium-ion Batteries

Nanostructured tin dioxide (SnO₂) has emerged as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity (1494 mA h g⁻¹) and excellent stability. Unfortunately, the rapid capacity fading and poor electrical conductivity of bulk SnO₂ material restrict its practical application. Here, SnO₂ nanospheres/reduced graphene oxide nanosheets (SRG) are fabricated through in-situ growth of carbon-coated SnO₂ using template-based approach. The nanosheet structure with the external layer of about several nanometers thickness can not only accommodate the volume change of Sn lattice during cycling but also enhance the electrical conductivity effectively. Benefited from such design, the SRG composites could deliver an initial discharge capacity of 1212.3 mA h g⁻¹ at 0.1 A g⁻¹, outstanding cycling performance of 1335.6 mA h g⁻¹ after 500 cycles at 1 A g⁻¹, and superior rate capability of 502.1 mA h g⁻¹ at 5 A g⁻¹ after 10 cycles. Finally, it is believed that this method could provide a versatile and effective process to prepare other metal-oxide/reduced graphene oxide (rGO) 2D nanocomposites.     

Synthesis and Electrochemical Performance of Electrostatic Self-Assembled Nano-Silicon@N-Doped Reduced Graphene Oxide/Carbon Nanofibers Composite as Anode Material for Lithium-Ion Batteries

Silicon-carbon nanocomposite materials are widely adopted in the anode of lithium-ion batteries (LIB). However, the lithium ion (Li⁺) transportation is hampered due to the significant accumulation of silicon nanoparticles (Si) and the change in their volume, which leads to decreased battery performance. In an attempt to optimize the electrode structure, we report on a self-assembly synthesis of silicon nanoparticles@nitrogen-doped reduced graphene oxide/carbon nanofiber (Si@N-doped rGO/CNF) composites as potential high-performance anodes for LIB through electrostatic attraction. A large number of vacancies or defects on the graphite plane are generated by N atoms, thus providing transmission channels for Li⁺ and improving the conductivity of the electrode. CNF can maintain the stability of the electrode structure and prevent Si from falling off the electrode. The three-dimensional composite structure of Si, N-doped rGO, and CNF can effectively buffer the volume changes of Si, form a stable solid electrolyte interface (SEI), and shorten the transmission distance of Li⁺ and the electrons, while also providing high conductivity and mechanical stability to the electrode. The Si@N-doped rGO/CNF electrode outperforms the Si@N-doped rGO and Si/rGO/CNF electrodes in cycle performance and rate capability, with a reversible specific capacity reaching 1276.8 mAh/g after 100 cycles and a Coulomb efficiency of 99%.     

氧化石墨烯水热还原前后的发光光谱

分别采用改进Hummers方法和水热还原法制备了氧化石墨烯(GO)和还原氧化石墨烯(RGO)。 GO和RGO经透射电子显微镜(TEM)、紫外-可见吸收光谱(UV-Vis)、红外光谱(IR)、荧光发射和激发光谱(PL、PLE)等技术手段进行了表征。 荧光发射光谱显示,氧化石墨烯(GO)在可见光的激发下可以得到波长在600~800 nm范围内的宽谱近红外荧光。 通过比较氧化石墨烯水热还原前后的光谱变化,发现氧化石墨烯近红外荧光起源于氧化石墨烯的表面含氧基团,如C=O、COOH。 近红外荧光穿透性好、对生物组织损坏小,非常适合于生物成像,预示着氧化石墨烯在生物成像方面的应用潜力。     

Nanohybridization of CoS2/MoS2 Heterostructure with Polyoxometalate on Functionalized Reduced Graphene Oxide for High-Performance LIBs

To address the poor cycling stability and low rate capability of MoS₂ as electrode materials for lithium-ion batteries (LIBs), herein, the CoS₂/MoS₂/PDDA-rGO/PMo₁₂ nanocomposites are constructed via a simple hydrothermal process, combining the advantages of all three, namely, CoS₂/MoS₂ heterojunction and polyoxometalates (POMs) provide abundant catalytically active sites and increase the multi-electron transfer ability, and the positively charged poly(diallyldimethylammonium chloride) modified reduced graphene oxide (PDDA-rGO) improve electronic conductivity and effectively prevent the aggregation of MoS₂, meanwhile stabilize the negatively charged [PMo₁₂O₄₀]³⁻. After the electrochemical testing, the resulting CoS₂/MoS₂/PDDA-rGO/PMo₁₂ nanocomposite achieved 1055 mA h g⁻¹ initial specific capacities and stabilized at 740 mA h g⁻¹ after 150 cycles at 100 mA g⁻¹ current density. And the specific capacities of MoS₂, MoS₂/PDDA-rGO, CoS₂/MoS₂, and CoS₂/MoS₂/PDDA-rGO were 201, 421, 518, and 589 at 100 mA g⁻¹ after 150 cycles, respectively. The fact of the greatly improving capacity of MoS₂-based nanocomposites suggests its potential for high performance electrode materials of LIBs. Moreover, the lithium storage mechanism of CoS₂/MoS₂/PDDA-rGO/PMo₁₂ has been discussed on the basis of cyclic voltammetry with different scan rates.     

锂离子电池纳米氧化镍负极的制备及应用

应用水热法制备纳米氧化镍,观察样品形貌及研究电极电化学性能.结果表明,在水热合成过程中加入表面活性剂十二烷基硫酸钠（SDS）,可形成疏松多孔、表面呈蜂窝状、颗粒均匀（100～200 nm）的纳米氧化镍.0.1 A/g电流密度下,该纳米NiO电极首周期放电比容量高达2385.7 mAh/g,100周期之后电极比容量仍然稳...     

Three‐dimensional Nitrogen‐Doped Reduced Graphene Oxide/Carbon Nanotube Composite Catalysts for Vanadium Flow Batteries

The development of vanadium redox flow battery is limited by the sluggish kinetics of the reaction, especially the cathodic VO₂⁺/VO²⁺ redox couples. Therefore, it is vital to develop new electrocatalysts with enhanced activity to improve the battery performance. Herein, we synthesized the hydrogel precursor by a facile hydrothermal method. After the following carbonization, nitrogen‐doped reduced graphene oxide/carbon nanotube composite was obtained. By virtue of the large surface area and good conductivity, which are ensured by the unique hybrid structure, as well as the proper nitrogen doping, the as‐prepared composite presents enhanced catalytic performance toward the VO₂⁺/VO²⁺ redox reaction. We also demonstrated the composite with carbon nanotube loading of 2 mg/mL exhibits the highest activity and remarkable stability in aqueous solution due to the strong synergy between reduced graphene oxide and carbon nanotubes, indicating that this composite might show promising applications in vanadium redox flow battery.     

具有高效电化学储能的中空网状笼还原氧化石墨烯

通过ZnO模板辅助电沉积法制备了中空网状笼还原氧化石墨烯,具有纳米管、多孔结构、网状结构和3D微米中空笼等多层次架构. 这样的结构能够同时促进电化学活性物种的传输,提高电极材料的利用率,以及提升超级电容器性能. 该类中空网状笼还原氧化石墨烯做超级充电器电极材料时表现出了优良的电化学性能,研究结果显示,在1.0 A•g^-1时比电容达到393 F•g^-1. 而且当电流密度从1.0 A•g^-1增加到20 A•g^-1,电容仅衰减了21.2%,10000周循环后比电容损失小于1%,表明具有优异的电容稳定性.     

Manganese Oxide/Graphene Aerogel Composites as an Outstanding Supercapacitor Electrode Material

Graphene aerogels (GA), prepared with an organic sol–gel process, possessing a high specific surface area of 793 m² g^?1, a high pore volume of 3 cm³ g^?1, and a large average pore size of 17 nm, were applied as a support for manganese oxide for supercapacitor applications. The manganese oxide was electrochemically deposited into the highly porous GA to form MnO₂/GA composites. The composites, at a high manganese oxide loading of 61 wt. %, exhibited a high specific capacitance of 410 F g^?1 at 2 mV s^?1. More importantly, the high rate specific capacitances measured at 1000 mV s^?1 for these composites were two‐fold higher than those obtained with samples prepared in the absence of the GA support. The specific capacitance retention ratio, based on the specific capacitance obtained at 25 mV s^?1, was maintained high, at 85 %, even at the high scan rate of 1000 mV s^?1, in contrast with the significantly lower value of 67 % for the plain manganese oxide sample. For the cycling stability, the specific capacitance of the composite electrode decayed by only 5 % after 50,000 cycles at 1000 mV s^?1. The success of this MnO₂/GA composite may be attributed to the structural advantages of high specific surface areas, high pore volumes, large pore sizes, and three‐dimensionally well‐connected network of the GA support. These structural advantages made possible the high mass loading of the active material, manganese oxide, large amounts of electroactive surfaces for the superficial redox events, fast mass‐transfer within the porous structure, and well‐connected conductive paths for the involved charge transport.