Electrochemical investigation of silicon/carbon composite as anode material for lithium ion batteries

Silicon-graphite composites were prepared by mechanical ball milling for 20 h under argon protection. The microstructure and electrochemical performance of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy, and electrochemical experiments. XRD showed that the materials prepared by ball milling were composites consisting of Si and graphite powders. The composite electrode showed the best performance, especially when annealed at 200 °C for 2 h, which had a reversible capacity of 595 mAh g⁻¹ and an initial coulombic efficiency of 66%, and still retained 469 mAh g⁻¹ after 40 cycles with about 0.6% capacity loss per cycle.     

Electrodeposition of amorphous silicon anode for lithium ion batteries

Amorphous silicon has been successfully electrodeposited on copper using a SiCl₄ based organic electrolyte under galvanostatic conditions. The electrodeposited silicon films were characterized for their composition, morphology and structural characteristics using glancing angle X-ray diffraction (GAXRD), scanning electron microscopy (SEM), and Raman spectroscopy. GAXRD and Raman analyses clearly confirm the amorphous state of the deposited silicon film. The deposited films were tested for possible application as anodes for Li-ion battery. The results indicate that this binder free amorphous silicon anode exhibits a reversible capacity of ∼1300 mAh g⁻¹ with a columbic efficiency of >99.5% up to 100 cycles. Impedance measurements at the end of each charge cycle show a non-variable charge transfer resistance which contributes to the excellent cyclability over 100 cycles observed for the films. This approach of developing thin amorphous silicon films directly on copper eliminates the use of binders and conducting additives, rendering the process simple, facile and easily amenable for large scale manufacturing.     

Binder-free graphene/carbon nanotube/silicon hybrid grid as freestanding anode for high capacity lithium ion batteries

Light-weight graphene/Si (G/Si) hybrid binder-free electrode is deemed a high energy density anode contender for lithium ion batteries (LIBs). However, paper-like G/Si electrodes tend to show an increased migration distance for Li⁺ through the fast interlayer channel with the increment of electrode size, in addition to an intrinsically slow diffusion kinetics; thereby encumbering their commercial realisation in high energy density and long life LIBs. To address these problems, herein, sandwich-structured graphene/carbon nanotube/silicon (G/CNT/Si, Si: 56 wt.%, ∼500 nm) hybrid grid is designed, cognizant of its uniform and shorter Li⁺ migration distance. Cyclic voltammograms indicate G/CNT/Si paper and grid anode to exhibit good electrochemical activity at both low and high temperatures. Noteworthy is that the Li⁺ diffusion coefficient ratio between G/CNT/Si grid and paper anodes are 1.82, 1.64, 1.43, 1.36 and 1.53 at a temperature of −5, 10, 25, 40 and 55 °C, respectively. The initial coulombic efficiencies of both paper and grid anode are as high as ∼82%. After 60 cycles at 420 mA g⁻¹, the charge capacity of G/CNT/Si grid is retained at 808 mA h g⁻¹, which by far surpasses that of paper anode (i.e., 490 mA h g⁻¹). The attained lithium ion storage performance at both high and low temperatures, underpins the G/CNT/Si sandwiched grid as effective to realise the practical deployment of paper-like graphene electrodes for high energy density and long life LIBs.     

In situ self-assembled synthesis of polypyrrole-derived nitrogen-doped carbon nanotube reinforced graphene aerogels as high-performance anode materials for lithium ion batteries

Journal of Materials Science: Materials in Electronics - Three-dimensional aerogels assembled by interconnected 1D and 2D nanostructures building blocks have been anticipated as a prospective...     

锂离子二次电池负极材料的研究综述

总结了在碳材料、合金材料和复合材料等3个锂离子电池负极材料研发的主导方向上的开发情况和它们各自特点,描述了目前的研究所面临难题,给出了锂离子电池负极材料研发取得重大突破的可能途径和建议.     

竹基碳纤维/MoS2锂离子电池负极材料

随着电子产品、电动汽车以及智能电网的快速发展,不仅需要锂离子电池(LIBs)具有优异的储锂性能,而且要求电极材料成本低廉、资源丰富和绿色环保。基于碳负极材料的优点,将废弃的一次性竹筷,在碱性溶液中经过可控的热处理,利用竹子中丰富的天然纤维素,从而获得尺寸均匀的碳纤维(CFs)材料。相比于石墨电极,竹基CFs作为LIBs的负极材料时表现出优异的电化学性能。为进一步提高其储锂性能,以CFs为骨架,通过水热法在其表面制备了一层二硫化钼(MoS₂)纳米花,形成核壳结构的CFs/MoS₂复合电极材料。电化学测试结果表明,CFs电极在200 mA/g的电流密度下循环500次,放电比容量仍有381.1 mA·h/g;CFs/MoS₂复合材料在1 000 mA/g的大电流密度下经过1 000次循环,仍保持有843 mA·h/g的放电比容量。     

Low-temperature synthesis of nanosized disordered carbon spheres as an anode material for lithium ion batteries

Disordered carbons in the order of nanometers were prepared by a hydrothermal reaction route. X-ray diffraction studies indicated a highly disordered carbon structure. SEM and TEM results revealed that these disordered carbons have a perfect spherical morphology, smooth surface and uniform particle size of about 100 nm. The lithium intercalation property of the products was also investigated. The results showed that the products delivered lithium insertion and deinsertion capacities of 1233 and 491 mA h g^− 1 respectively during the first cycle. Subsequent cycles showed a remarkable improvement in cycling efficiency with a 10th cycle efficiency of 98%. The correlation between microstructure, morphology and electrochemical behavior of such carbons was discussed.     

新型锂电池负极复合材料硅/无定形碳/碳纳米管的制备及性能研究

通过高温裂解蔗糖混合纳米硅和碳纳米管,得到硅/无定形碳/碳纳米管复合材料.实验结果表明,复合材料的首次放电容量高达1315.4mAh/g,首次充放电效率为72.4%,经过20次充放电循环后可逆容量仍高达830.5mAh/g.具有良好弹性的碳纳米管组成的网状结构使复合材料能保持较好的形貌,而碳纳米管优良的导电性可以使更多...     

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.     

Electrochemical investigation on silicon/titanium carbide nanocomposite film anode for Li-ion batteries

A Si/TiC nanocomposite film was synthesized by a surface sol-gel method in combination with a following heat-treatment process. The electrochemical properties of the film anode for lithium ion batteries were investigated by galvanostatic charge-discharge tests, cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). Because of the homogeneous distribution of Si active particles in TiC matrix, the Si/TiC composite showed reversible lithium storage capacities of about 1000 and 1300 mAh g^− 1 at 160 and 80 mA g^− 1 even after 80 cycles, respectively. Using two-parallel diffusion path model, the reactive mechanisms of Li with Si/TiC composite film were interpreted. The chemical diffusion coefficients of the Si/TiC nanocomposite film at different electrode potentials were also discussed.     

P25/graphene nanocomposites as a high-performance anode material for lithium ion batteries

P25/graphene nanocomposites were successful synthesized in a water-ethanol solvent under hydrothermal conditions. During the process of the reduction of GO into graphene (GR), the P25 nanoparticles were decorated on graphene sheets simultaneously. Moreover, the GR content in the as-synthesized nanocomposites can be easily adjusted by changing the dosage of P25. The interesting P25/GR nanocomposites were found to be a promising anode material for lithium-ion batteries and showed significantly enhanced Li-ion insertion/extraction performance. The optimal weight percentage of GR was found to be 29.9%, which resulted in a high capacity of 282.8 mAh g⁻¹ after 50 cycles at a current rate of 0.5 C. The improved capacity may be attributed to the synergetic effect between graphene sheets and P25 nanoparticles.     

锰氧化物/石墨烯复合材料作为锂离子电池负极的研究

以天然石墨为原料,采用改进的Hummers法合成含Mn的氧化石墨;400℃条件下氢气还原制备了锰氧化物/石墨烯复合材料。利用XRD、SEM和TEM对所制备的复合材料进行了表征。结果表明锰氧化物(MnOx)颗粒均匀地分布在石墨烯片层表面。将复合材料作为锂离子电池负极进行研究,在50mA/g电流密度下,首次库伦效率为70.4%,可逆容量达876mAh/g,并且具有良好的循环性能,在30次循环后仍保持在700mAh/g以上。     

锂离子电池负极墨水的制备及性能研究

钛酸锂因零应变特性已成为性能优异的锂离子电池负极材料,在锂离子电极负极材料有良好的应用前景,确保后期3D打印出性能良好的微电池棒状电极.选取钛酸锂作为棒状电极的负极材料,与溶剂、增稠剂、分散剂和保湿剂等按一定比例制备打印墨水,随后通过以挤压为基础的3D打印技术打印电极,并在氮气保护下高温烧结获得的棒状电极。本文主要探究了钛酸锂掺杂石墨、钛酸锂质量分数以及烧结温度对棒状电极的性能影响,其次通过打印墨水的流变特性模拟分析来探究墨水黏度对挤压过程中流动速度的影响.结果表明:掺杂10%石墨的钛酸锂棒状电极相比未掺杂石墨的电极,其充放电容量提高了18%,表现出较好的循环性能;当钛酸锂质量分数为59%,打印墨水黏度为26.53 Pa·s,所制备棒状电极的电阻率为221 kΩ·cm,打印墨水具有良好的打印及导电性能;当烧结温度为950℃,棒状电极电阻率较小,为205 kΩ·cm,与基板有良好的附着力,膜层表面平整、致密且有许多孔洞,有助于电解液的渗透.对打印墨水的黏度进行模拟分析可知,随黏度的增减而使墨水流动速度变化明显.     

Chemically activated graphene/porous Si@SiOx composite as anode for lithium ion batteries

Chemically activated graphene/porous Si@SiO_x (CAG/Si@SiO_x) composite has been synthesized via magnesiothemic reduction of mesoporous SiO₂ (MCM-48) to porous Si@SiO_x and dispersing in the suspension of chemically activated graphene oxide (CAGO) followed by thermal reduction. The porous Si@SiO_x particles are well encapsulated in chemically activated graphene (CAG) matrix. The resulting CAG/Si@SiO_x composite exhibits a high reversible capacity and excellent cycling stability up to 763 mAh g⁻¹ at a current density of 100 mA g⁻¹ after 50 cycles. The porous structure of CAG layer and Si@SiO_x is beneficial to accommodate volume expansion of Si during discharge and charge process and the interconnected CAG improves the electronic conductivity of composite.     

碳纳米管/中间相炭微球复合材料锂离子电池负极材料研究

采用热缩聚法(温度为420℃、反应时间为2 h)制备出碳纳米管/中间相炭微球复合材料。研究了碳纳米管添加量对中间相炭微球的形成和形貌的影响,以及对碳纳米管/中间相炭微球复合材料充放电性能的影响。实验结果表明,5%(质量分数)的碳纳米管添加量有利于中间相炭微球的形成,碳纳米管/中间相炭微球复合材料作为负极材料的锂离子电池充放电容量可达到337 mAh/g,20次循环后容量仍保持88%。     

In situ synthesis of SnO2/graphene nanocomposite and their application as anode material for lithium ion battery

SnO₂/graphene nanocomposite was prepared via an in situ chemical synthesis method. The nanocomposite was characterized by X-ray diffraction, filed emission scanning electron microscope and transmission electron microscope, which revealed that tiny SnO₂ nanoparticles could be homogeneously distributed on the graphene matrix. The electrochemical performance of the SnO₂/graphene nanocomposite as anode material was measured by galvanostatic charge/discharge cycling. The SnO₂/graphene nanocomposite showed a reversible capacity of 665 mAh/g after 50 cycles and an excellent cycling performance for lithium ion battery, which was ascribed to the three-dimensional architecture of SnO₂/graphene nanocomposite. These results suggest that SnO₂/graphene nanocomposite would be a promising anode material for lithium ion battery.     

SnO2 nanoparticles distributed on multi-walled carbon nanotubes and ball-milled graphite as anode materials of lithium ion batteries

SnO2 nanoparticles were supported on ball-milled graphite (BMG) or carbon nanotubes (CNTs) using a chemical reduction method with ethylene glycol, and the electrochemical properties of the nanocomposites were evaluated as anode active materials of lithium-ion batteries. The BMG and CNTs contributed to an increase in both the capacity enhancement and cyclic stability compared to that of commercial graphite. In particular, the mixture electrode of SnO2/BMG:SnO2/CNT = 3:1 (in weight ratio) showed higher performance in the reversible capacity and cyclic stability than did the SnO2/BMG and SnO2/CNT electrodes. This might be resulted from the network formation for excellent electronic path by CNT distributed on SnO2/BMG composites.     

Molten-salt decomposition synthesis of SnO2 nanoparticles as anode materials for lithium ion batteries

SnO₂ nanoparticles were synthesized by a simple, easily scaled-up molten-salt decomposition method with SnSO₄ as the molten salt and the reactive phase. During the synthesis process, the undecomposed molten SnSO₄ makes it possible to obtain SnO₂ nanoparticles by serving as the dispersion medium and keeping the particles from aggregation. The as-prepared SnO₂ had a tetragonal rutile structure with an average particle size of 50 nm. When used as anode materials for lithium ion battery, SnO₂ nanoparticles retained the charge capacity still as high as 402 mAh g^? 1 at a current density of 156 mA g^? 1 after 40 cycles. Moreover, cyclic voltammograms tests showed the formation/deformation of Li₂O was partially reversible.