In situ synthesis of SnO2 nanosheet/graphene composite as anode materials for lithium-ion batteries

A novel SnO₂/graphene composite has been synthesized via an in situ chemical synthesis method, in which single crystal SnO₂ nanosheets are uniformly grown on graphene support. The as-prepared products were characterized by X-ray diffraction, field emission scanning electron microscope, transmission electron microscope, Thermogravimetric analyses and Nitrogen adsorption/desorption. When used as an anode material for lithium ion batteries, the SnO₂/graphene composite exhibits an enhanced reversible lithium storage capacity and good cyclic performance. The first discharge and charge capacities are 1,366 and 975 mAh g^?1, respectively. After 100 cycles, the reversible discharge capacity is still maintained at 451 mAh g^?1 at the current densities of 100 mA g^?1, indicating that it’s a promising anode material for high performance lithium ion batteries.     

Polycrystalline SnO2 nanowires coated with amorphous carbon nanotube as anode material for lithium ion batteries

One-dimensional (1D) SnO₂ nanowires, coated by in situ formed amorphous carbon nanotubes (a-CNTs) with a mean diameter of ca. 60 nm, were synthesized by annealing the anodic alumina oxide (AAO) filled with a sol of SnO₂. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns revealed that the prepared SnO₂ nanowires exist in polycrystalline rutile structure. The coating of carbon nanotubes has some defects on the wall after the internal SnO₂ nanoparticles were removed. The 1D SnO₂ nanowires present a reversible capacity of 441 mAh/g and an excellent cycling performance as an anode material for lithium ion batteries. This suggests that 1D nanostructured materials have great promise for practical application.     

Carbon nanotubes anchored with SnO2 nanosheets as anode for enhanced Li-ion storage

The carbon nanotubes (CNTs) anchored with SnO₂ nanosheets were prepared using a hydrothermal method. The as-prepared products were characterized by X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analyses, field emission scanning electron microscope and transmission electron microscope. The electrochemical performances of SnO₂ nanosheets/CNTs composite were measured by galvanostatic charge/discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the SnO₂ nanosheets/CNTs composite maintains high lithium storage capacity and good cycling stability. The designed structure plays key role in improving electrochemical performance. The CNTs anchored with SnO₂ nanosheets will be an ideal candidate of anode material for lithium ion batteries.     

Microporous carbon derived from polyaniline base as anode material for lithium ion secondary battery

Microporous carbon with large surface area was prepared from polyaniline base using K₂CO₃ as an activating agent. The physicochemical properties of the carbon were characterized by scanning electron microscope, X-ray diffraction, Brunauer-Emmett-Teller, elemental analyses and X-ray photoelectron spectroscopy measurement. The electrochemical properties of the microporous carbon as anode material in lithium ion secondary battery were evaluated. The first discharge capacity of the microporous carbon was 1108 mAh g⁻¹, whose first charge capacity was 624 mAh g⁻¹, with a coulombic efficiency of 56.3%. After 20 cycling tests, the microporous carbon retains a reversible capacity of 603 mAh g⁻¹ at a current density of 100 mA g⁻¹. These results clearly demonstrated the potential role of microporous carbon as anode for high capacity lithium ion secondary battery.     

SnO<Subscript>2</Subscript>/graphene composite with high lithium storage capability for lithium rechargeable batteries

SnO₂/graphene nanocomposites have been fabricated by a simple chemical method. In the fabrication process, the control of surface charge causes echinoid-like SnO₂ nanoparticles to be formed and uniformly decorated on the graphene. The electrostatic attraction between a graphene nanosheet (GNS) and the echinoid-like SnO₂ particles under controlled pH creates a unique nanostructure in which extremely small SnO₂ particles are uniformly dispersed on the GNS. The SnO₂/graphene nanocomposite has been shown to perform as a high capacity anode with good cycling behavior in lithium rechargeable batteries. The anode retained a reversible capacity of 634 mA·h·g⁻¹ with a coulombic efficiency of 98% after 50 cycles. The high reversibility can be attributed to the mechanical buffering by the GNS against the large volume change of SnO₂ during delithiation/lithiation reactions. Furthermore, the power capability is significantly enhanced due to the nanostructure, which enables facile electron transport through the GNS and fast delithiation/lithiation reactions within the echinoid-like nano-SnO₂. The route suggested here for the fabrication of SnO₂/graphene hybrid materials is a simple economical route for the preparation of other graphene-based hybrid materials which can be employed in many different fields.     

Structure and electrochemical performance of Fe3O4/graphene nanocomposite as anode material for lithium-ion batteries

Using hydrothermal method, Fe₃O₄/graphene nanocomposite is prepared by synthesizing Fe₃O₄ particles in graphene. The synthesized Fe₃O₄ is nano-sized sphere particles (100–200 nm) and uniformly distributed on the planes of graphene. Fe₃O₄/graphene nanocomposite as anode material for lithium ion batteries shows high reversible specific capacity of 771 mAh g⁻¹ at 50th cycle and good rate capability. The excellent electrochemical performance of the nanocomposite can be attributed to the high surface area and good electronic conductivity of graphene. Due to the high surface area, graphene can prevent Fe₃O₄ nanoparticles from aggregating and provide enough space to buffer the volume change during the Li insertion/extraction processes in Fe₃O₄ nanoparticles.     

用于锂离子电池的高性能SiOx/C/石墨烯复合负极材料

以SiO、丁苯橡胶(SBR)及石墨烯为原料,通过高温歧化、机械球磨、喷雾干燥和高温热解制备电化学性能优异的锂离子电池SiO_x/C/石墨烯复合负极材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线能谱仪(EDS)和恒流充放电测试仪对复合材料的物相、颗粒形貌及电化学性能等进行表征。结果表明,热解后的SiO_x/C/石墨烯复合负极材料的首次放电容量为1 807mAh/g,100次循环后,可逆容量高达1 349mAh/g,库伦效率为99.1%,循环稳定性远高于SiO_x/C和SiO_x/C/graphene前驱体,具有良好的倍率性能。     

SnO2-reduced graphene oxide nanoribbons as anodes for lithium ion batteries with enhanced cycling stability

A nanocomposite material of SnO2-reduced graphene oxide nanoribbons has been developed. In this composite, the reduced graphene oxide nanoribbons are uniformly coated by nanosized SnO2 that formed a thin layer of SnO2 on the surface. When used as anodes in lithium ion batteries, the composite shows outstanding electrochemical performance with the high reversible discharge capacity of 1,027 mAh/g at 0.1 A/g after 165 cycles and 640 mAh/g at 3.0 A/g after 160 cycles with current rates varying from 0.1 to 3.0 A/g and no capacity decay after 600 cycles compared to the second cycle at a current density of 1.0 A/g. The high reversible capacity, good rate performance and excellent cycling stability of the composite are due to the synergistic combination of electrically conductive reduced graphene oxide nanoribbons and SnO2, The method developed here is practical for the large-scale development of anode materials for lithium ion batteries.     

Chemical bath deposition of SnS2 nanowall arrays with improved electrochemical performance for lithium ion battery

A facile chemical bath deposition (CBD) approach has been developed to fabricating SnS₂ nanowall (NW) arrays directly on copper foils. As an anode material for lithium ion battery, the NW arrays exhibit enhanced lithium ion storage property. At a rate of 0.3 C, the NW arrays maintain a capacity of about 700 mA h g⁻¹ after 40 cycles. Even at a high rate of 1.2 C, the NW arrays can still deliver a stable capacity of 400 mA h g⁻¹. The high electrochemical performance is well related to the in situ growth of uniform SnS₂ nanostructures on a conductive copper current collector, which results in a robust adhesion for the SnS₂ NW on the copper, and leads to an enhanced electron conductivity, improved lithium ion transport, and sustained volume variations.     

Facile synthesis of α-MnO2/graphene nanocomposites and their high performance as lithium-ion battery anode

α-MnO₂/graphene nanocomposites are synthesized via a facile wet-chemical route, and α-MnO₂ nanosheets are uniformly distributed on the surface of graphene. Their high performance as lithium ion battery anodes is obtained. Their reversible capacity at C/10 rate is up to 726.5 mA h/g, and maintains up to 635.5 mA h/g after 30 cycles. Such a performance can be partly attributed to high electron conductivity, excellent flexibility and high specific surface area of graphene. Also, α-MnO₂ nanostructures can play a role in preventing the pile of graphene nanosheets with the loss of their active surface area. The present results indicate that α-MnO₂/graphene nanocomposites have potential applications in lithium-ion battery anodes.     

Morphology effect on the performances of SnO2 nanorod arrays as anodes for Li-ion batteries

Ni foam suppported-SnO₂ nanorod arrays with controllable diameter were prepared via a template-free growth method, which was a convenient route for the large-scale growth of pure-phase metal oxide nanorod arrays on metal substrates. The relationship between electrochemical behavior and the shape of SnO₂ nanorod arrays has been investigated in detail. SnO₂ nanorod arrays with diameter of about 25 nm, as anode materials for Li-ion batteries revealed a capacity of 607 mAh g⁻¹ (at 0.2 C) up to 50 cycles. The superior performance of the SnO₂ nanorods can be mainly attributed to small size of nanorods which reduce volume expansion and lithium diffusion length.     

表面活性剂对纳米SnO2负极材料形貌结构及电化学性能的影响

为了提高SnO_2负极材料的电化学性能,本文以锡酸钠为原料、聚乙烯吡咯烷酮(PVP)、尿素、十二烷基硫酸钠(SDS)分别作为表面活性剂,采用水热法制备了具有纳米结构的SnO_2负极材料.利用扫描电子显微镜(SEM)、X射线衍射(XRD)、电化学测试仪测试了材料的形貌、结构和电化学性质.结果表明,使用不同表面活性剂,可获得不同形貌的纳米结构,并且对材料的电化学性能有较大的影响.当尿素作表面活性剂时,获得了分散较好的球形材料,在0.01~3.0 V,以200 mA/g进行充放电测试,首次放电容量2 256.6 mAh/g,经过50次循环后,放电容量保持在440 mAh/g,表现了较好的循环性能.     

CTAB-assisted sol-gel synthesis of Li4Ti5O12 and its performance as anode material for Li-ion batteries

A simple CTAB-assisted sol-gel technique for synthesizing nano-sized Li₄Ti₅O₁₂ with promising electrochemical performance as anode material for lithium ion battery is reported. The structural and morphological properties are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemical performance of both samples (with and without CTAB) calcined at 800 °C is evaluated using Swagelok™ cells by galvanostatic charge/discharge cycling at room temperature. The XRD pattern for sample prepared in presence of CTAB and calcined at 800 °C shows high-purity cubic-spinel Li₄Ti₅O₁₂ phase (JCPDS # 26-1198). Nanosized-Li₄Ti₅O₁₂ calcined at 800 °C in presence of CTAB exhibits promising cycling performance with initial discharge capacity of 174 mAh g⁻¹ (∼100% of theoretical capacity) and sustains a capacity value of 164 mAh g⁻¹ beyond 30 cycles. By contrast, the sample prepared in absence of CTAB under identical reaction conditions exhibits initial discharge capacity of 140 mAh g⁻¹ (80% of theoretical capacity) that fades to 110 mAh g⁻¹ after 30 cycles.     

三维石墨烯纳米球的制备及其在锂离子电池中的应用

采用直流电弧放电法制备出一种三维石墨烯纳米球材料。采用扫描电镜(SEM)、透射电镜(TEM)、拉曼光谱和X射线衍射光谱(XRD)等测试方法对三维石墨烯纳米球的形貌和结构进行了表征和研究。通过交流阻抗(EIS)、恒流充放电和循环稳定性测试等电化学测试手段来研究三维石墨烯纳米球作为锂离子电池负极材料的电化学性能。结果表明, 在电流密度为0.05 A/g下, 三维石墨烯纳米球作为锂离子电池负极材料的首次放电容量为485.9 mAh/g, 高于炭黑作负极的放电容量(401 mAh/g); 当电流密度为1 A/g时, 三维石墨烯纳米球负极材料仍然具有185.4 mAh/g的放电容量。在电流密度分别为0.5 A/g和2.5 A/g下, 充放电循环100次以后, 三维石墨烯纳米球的比容量几乎没有衰减, 这表明三维石墨烯纳米球作为锂离子电池的负极材料比炭黑具有更大的容量, 同时具有优异的循环稳定性。     

Facile synthesis and electrochemical properties of porous SnO2 micro-tubes as anode material for lithium-ion battery

Porous SnO₂ micro-tubes were synthesized by the thermal decomposition of SnC₂O₄ precursor. The morphology of SnC₂O₄ could be preserved after the controlled heat treatment and a lot of mesopores left due to the release of gases. The mesoporous nature with a range of 3-50 nm was characterized by BET method. SEM images showed that the obtained SnO₂ samples were rhombic tube-like with swallow-tailed nozzles. When the porous SnO₂ micro-tubes were used as anode materials for lithium-ion battery, they exhibited high lithium storage capacity and coulomb efficiency. In addition, CV results demonstrated that the formation of Li₂O at high voltage was partially reversible reactions.     

Phosphorus Enhanced Intermolecular Interactions of SnO2 and Graphene as an Ultrastable Lithium Battery Anode

SnO₂ suffers from fast capacity fading in lithium‐ion batteries due to large volume expansion as well as unstable solid electrolyte interphase. Herein, the design and synthesis of phosphorus bridging SnO₂ and graphene through covalent bonding are demonstrated to achieve a robust structure. In this unique structure, the phosphorus is able to covalently “bridge” graphene and tin oxide nanocrystal through P? C and Sn? O? P bonding, respectively, and act as a buffer layer to keep the structure stable during charging–discharging. As a result, when applied as a lithium battery anode, SnO₂@P@GO shows very stable performance and retains 95% of 2nd capacity onward after 700 cycles. Such unique structural design opens up new avenues for the rational design of other high‐capacity materials for lithium battery, and as a proof‐of‐concept, creates new opportunities in the synthesis of advanced functional materials for high‐performance energy storage devices.     

纳米二氧化锡/三维大孔石墨烯复合电极的制备及其储锂性能的研究

以维生素C(VC)为还原剂,通过溶剂热还原法制备了纳米二氧化锡/三维大孔石墨烯复合负极材料(SnO_2/3DGr)。SEM和TEM测试表明,SnO_2/3DGr具有均匀分布的微米级孔隙,其中SnO_2晶粒尺寸为6~8nm,且均匀分布在石墨烯片层表面。电化学测试表明所制备的SnO_2/3DGr复合电极材料具有优异的电化学性能,该材料在电流密度为100mA/g时,循环100周之后仍然具有1678mAh/g的可逆比容量,在极高电流密度5A/g下,仍然保持405mAh/g的可逆比容量,表现出非常优异的循环稳定性和倍率性能。该材料独特的三维大孔结构以及SnO_2与石墨烯的协同作用,很好地抑制了SnO_2在循环过程中的体积效应,大大改善了SnO_2负极材料的电化学性能。     

Nanocomposite por-Si/SnOx layers formation for gas microsensors

Hetero-phase nanocomposite layers based on porous silicon and nonstoichiometric tin oxide (por-Si/SnO_x) were obtained by the chemical vapor deposition (CVD), magnetron sputtering, and molecular layer deposition methods. The structure, and the atomic and phase compositions of the nanocomposites were studied by means of transmission electron microscopy, energy-dispersive X-ray analysis (EDX), scanning electron microscopy, Raman spectroscopy, Auger spectroscopy, and X-ray photoelectron spectroscopy. The obtained data were indicative of the formation of por-Si/SnO_x nanocomposite layers up to 2 μm thick with x = 1.0-2.0. According to EDX data, in magnetron sputtering process the formation of por-Si/SnO_x nanocomposite layers proceeds on the externally exposed surface of polycrystalline por-Si skeleton elements with subsequent diffusion of tin atoms into the pores along the por-Si walls. The other two methods lead to formation of large SnO_x islands covering pores in the por-Si structure. Enhanced diffusion of tin atoms into porous matrix with D_eff ≈ 1 × 10⁻¹⁴ cm²/s was observed in samples annealed at 500 °C. Sensor heterostructures based on magnetron sputtered por-Si/SnO_x nanocomposite layers show high sensitivity to NO₂ environmental molecules and remarkable stability, thus offering promise in gas sensing applications.     

Preparation and characterization of SnO2/carbon nanotube composite for lithium ion battery applications

SnO₂/multi-walled carbon nanotube (MWCNT) composite was prepared via a diffusion method. Firstly the MWCNT was sonicated in a filtrate which was derived from a tin dichloride solution mixed with AgNO₃ solution. Then the SnO₂/MWCNT composite was prepared whereby, after calcination in N₂ atmosphere, the salts inside the MWCNT decomposed to SnO₂. The resulting composite was characterized by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, which indicated that SnO₂ had infiltrated into the MWCNT and filled the interior. The subsequent evaluation of the electrochemical performance in lithium ion batteries showed that the SnO₂/MWCNT composite had a reversible discharge capacity of 505.9 mAh?g^− 1 after 40 cycles, as compared to 126.4 mAh?g^− 1 for pure nano-SnO₂.     

锂离子电池SiOx/C/CNTs复合负极材料的制备及其电化学性能

通过机械球磨、喷雾干燥和高温热解制备锂离子电池SiO_x/C/CNTs复合负极材料,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线能谱仪(EDS)和恒流充放电测试仪,对其物相组成、颗粒形貌及电化学性能进行了表征,并与SiO_x/C和SiO_x/C/石墨烯复合材料的性能对比。研究结果表明,CNTs的引入不仅可以增加复合材料的可逆容量,还可以有效提高材料的循环稳定性。SiO_x/C/CNTs复合负极材料在100mA/g下首次放电比容量为1 981.5mAh/g,循环100周后,放电容量仍有474.0mAh/g,倍率性能较优,具有良好的应用前景。