首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 140 毫秒
1.
表面修饰SrTiO3光催化剂纳米碳管的光电化学嵌锂特性   总被引:1,自引:0,他引:1  
采用直接水解沉淀的方法制备了钙钛矿型SrTiO3纳米粒子,并将其修饰在纳米碳管表面形成SrTiO3/CNTs纳米复合材料,研究了SrTiO3/CNTs电极在氙灯照射下的光电化学嵌锂特性.实验结果表明,光照射对CNTs电极的嵌锂容量影响不大,而SrTiO3/CNTs电极受光照时的嵌锂容最高达251 mAh/g,远高于无光照下的嵌锂容量(170 mAh/g).循环伏安测试也表明光照射可显著提高嵌脱锂反应电流.这可归因于SrTiO3光催化剂受光照射而诱发的纳米碳管嵌锂反应.  相似文献   

2.
竹节状纳米碳纤维的制备及嵌锂性能研究   总被引:4,自引:0,他引:4  
以泡沫镍为催化剂 ,在 6 0 0和 70 0℃下 ,以CVD法热解乙炔气体制备大量的纳米碳纤维 .随着制备温度增加 ,纳米碳纤维直径变小 ,竹节状含量减少 ,d0 0 2 值减小 ,微晶片层平面Lc 和La 值增大 ,碳材料的可逆容量则下降 .分别用透射电镜、X射线衍射和拉曼光谱观察和测定了纳米碳纤维的形貌、微结构 ,发现在不同条件下生长的纳米碳纤维有不同的形貌和结构 .对纳米碳纤维的电化学嵌锂性能的研究表明 ,纳米碳纤维的结构对其电化学嵌锂容量和充放电循环寿命起重要影响 ,制备温度越低 ,纳米碳纤维的石墨化程度越差 ,可逆嵌锂容量相应要高一些  相似文献   

3.
通过V2O5的碳热还原反应制备了具有优异倍率性能和循环稳定性的V2O3-C双层包覆的磷酸铁锂正极材料. 粉末X射线衍射、元素分析、高分辨投射电镜和拉曼光谱研究表明V2O3相与碳层共包覆于磷酸铁锂颗粒表面. 在V2O5的碳热还原反应后,碳含量明显降低,但石墨化程度未发生明显改变. 电化学测试结果表明少量V2O3显著改善了磷酸铁锂正极材料的倍率性能和高温循环性能,包含1%氧化钒的复合正极材料在0.2 C放电容量为167 mAh/g,5 C时放电容量为129 mAh/g,并且循环稳定性优异;在55 oC和1 C时放电容量为151 mAh/g,循环100次后无明显容量衰减.  相似文献   

4.
侯贤华  胡社军  石璐 《物理学报》2010,59(3):2109-2113
采用磁控溅射沉积技术制备了纳米级Sn-Ti合金负极材料,并用X射线衍射和扫描电子显微镜进行表征,用高精度电池测试系统进行充放电和循环伏安测试.结果表明先镀Sn后镀Ti(Sn/Ti复合膜)和先镀Ti后镀Sn(Ti/Sn复合膜)具有很大的性能差异,其中Sn/Ti复合膜具有优异的循环稳定性和较高的可逆容量.首次放电容量和充电容量分别为9275 mAh/g和6954 mAh/g,首次库仑效率为75%,经30次循环后,该电极的放电容量保持为4152 mAh/g,这主要归因于活性物质Sn与电解液界面之间存在非活 关键词: 锂离子电池 磁控溅射 Sn-Ti合金 电化学性能  相似文献   

5.
利用固相法合成了钠掺杂的LiFePO4,结构表征显示钠离子成功地掺入到了晶格中.SEM显示其粒径在1~3 μm.XRD显示钠掺杂样品晶胞变大.电池测试表明样品0.1 C放电150 mAh/g,5和7.5 C下分别放电109和107 mAh/g.1和5 C循环时,与初始放电容量相比,样品容量保持率分别为84%(1000次循环后)和86%(350次循环后),表现了优异的结构稳定性和循环性能.研究表明钠离子掺杂可以有效地提高磷酸铁锂的电化学活性,尤其是循环性能.  相似文献   

6.
纳米碳管的分叉结构   总被引:4,自引:0,他引:4       下载免费PDF全文
应用催化剂热解碳氢气及热丝CVD两种不同的方法制备了含有分叉结构的纳米碳管,并用透射电镜考察了分叉碳管的形貌及微结构特征.结果表明:分叉结构的形态与制备方法有关,前者沿生长方向的呈规则节突状分布,而后者的分支碳管与未分支的形态类同.纳米碳管分叉结构的形成可能与制备条件的扰动有关,并因此改变其输运特性. 关键词:  相似文献   

7.
人工裁剪制备石墨纳米结构   总被引:1,自引:0,他引:1       下载免费PDF全文
采用不同的方法裁剪高定向热解石墨(HOPG),制备纳米尺寸的石墨条.首先,发现用聚焦离子束(镓离子)刻蚀高定向热解石墨,可以得到边缘整齐程度在几十纳米的石墨条,另外,用 电子束曝光和反应离子刻蚀的工艺,可以得到最小尺寸为50 nm的纳米石墨图型 (nano-size d graphite pattern,纳米尺寸的多层石墨结构).采用了三种不同的方案制备反应等离子刻 蚀过程中需要的掩膜,分别是PECVD生长的SiO2掩膜,磁控溅射的方法生长的Si O2掩膜和PMMA光刻胶掩膜,并将三种方案的刻蚀结果做了对比. 关键词: 高定向热解石墨 聚焦离子束刻蚀 电子束曝光 反应离子刻蚀  相似文献   

8.
采用燃烧法制备了Fe/Mo/MgO催化剂,用化学气相沉积法在1000℃下催化裂解甲烷制得了单壁纳米碳管.实验结果表明,550℃下焙烧的催化剂效果最好,适宜的酸碱性应该是催化剂具有较高活性的原因.用扫描电镜、透射电镜、高分辨透射电镜、热重分析和拉曼光谱等方法对制备的纳米碳管粗产品进行了表征.结果表明,该产物确为高质量单壁纳米碳管,其形态基本都以束状存在,且单壁纳米碳管直径分布较窄(0.85~1.22nm);对反应气氛的考察表明,CH4/N2=50/300为最佳,该气氛下所制得粗产物中单壁碳管的含量接近40%,经稀盐酸室温处理后,碳管含量可达到75%以上.  相似文献   

9.
李娟  汝强*  孙大伟  张贝贝  胡社军  侯贤华 《物理学报》2013,62(9):98201-098201
以酸处理的中间相碳微球(MCMB)为载体, 用化学还原法在碳球表面沉积SnSb合金, 合成SnSb 包覆碳球的核壳结构负极材料. 采用XRD, SEM技术对材料的结构和形貌进行了表征, 用恒电流充放电(CC)、循环伏安(CV)和交流阻抗(EIS)测试了材料的电化学性能. 实验结果表明: SnSb/MCMB样品呈现纳米晶与非晶态的混合组织; 单一SnSb合金的容量衰减较快, 而对于SnSb/MCMB复合材料, 细小的合金颗粒均匀钉扎在MCMB表面, 不仅改善了颗粒的团聚现象, 而且增强了材料的导电能力, 使材料的循环稳定性得到改善, 复合材料具有936.161 mAh/g的首次放电比容量, 首次库仑效率80.3%, 50次循环后容量维持在498.221 mAh/g. 关键词: SnSb合金 锂离子电池 中间相碳微球(MCMB) 电化学性能  相似文献   

10.
新能源交通工具的飞速发展激发了人们对高能量密度电池技术的探索,锂硫电池因为具有较高的理论能量密度被视为锂离子电池的替代品。但由于硫具有导电性差和多硫化物的穿梭效应等问题,锂硫电池的商业化应用仍面临巨大的挑战。基于此,为改善锂硫电池的性能,设计了一种高导电性三维支撑的正极结构:多级交联的三维导电网络能够有效提高正极材料导电性;纳米碳球堆叠形成的孔道结构提供了丰富的反应活性点位和体积缓冲空间。测试结果表明,这种新型正极结构在0.15 C的电流倍率下放电比容量高达1 124 mAh g-1;在2 C的大电流倍率充放电200次循环后,放电比容量仍能保持在591 mAh g~(-1),表现出良好的循环稳定性和电化学稳定性。  相似文献   

11.
Zhijun Jia  Jiawei Hao  Lujing Liu  Yi Wang  Tao Qi 《Ionics》2018,24(11):3483-3491
In this work, vertically aligned α-MnO2 nanosheets on carbon nanotubes are synthesized simply by a solution process and the electrochemical performance as host materials of magnesium ion is tested in aqueous solution. Cyclic voltammetry analysis confirms the enhanced electrochemical activity of carbon nanotube-supported samples. Moreover, carbon nanotubes skeleton could reduce the charge transfer resistant of the cathode materials, which is confirmed by electrochemical impedance spectroscopy. Furthermore, when tested as magnesium ion batteries cathodic electrode, the α-MnO2/carbon nanotube sample registers a prominent discharge capacity of 144.6 mAh g?1 at current density of 0.5 A g?1, which is higher than the discharge capacity of α-MnO2 (87.5 mAh g?1) due to the synergistic effect of insertion/deinsertion reaction and physical adsorption/desorption process. After the 1000th cycle, a remarkable discharge capacity of 48.3 mAh g?1 is collected for α-MnO2/carbon nanotube at current density of 10 A g?1, which is 85% of the original. It is found that the carbon skeleton not only improved the capacity but also enhanced the cycling performance of the α-MnO2 electrode significantly. Therefore, α-MnO2/carbon nanotube is a very promising candidate for further application in environmentally benign magnesium ion batteries.  相似文献   

12.
Anode material for lithium-ion battery based on Sn/carbon nanotube (CNT) composite is synthesized via a chemical reduction method. The Sn/CNT composite is characterized by thermogravimetry, X-ray diffraction, and transition electron microscopy. The Sn/CNT composite delivers high initial reversible capacity of 630.5 mAh g?1 and exhibits stable cycling performance with a reversible capacity of 413 mAh g?1 at the 100th cycle. The enhanced electrochemical performance of the Sn/CNT composite could be mainly attributed to the well dispersion of Sn nanoparticles on CNT and partially filling Sn nanoparticles inside the CNT. It is proposed that the chemical treatment of CNT with concentrated nitric acid, which cuts carbon nanotube into short pieces and increases the amount of oxygen-functional groups on the surface, plays an important role in the anchoring of Sn nanoparticles on carbon nanotube and inhibiting the agglomeration of Sn nanoparticles during the charge–discharge process.  相似文献   

13.
Silicon (Si) shows overwhelming promise as the high-capacity anode material of Li-ion batteries with high energy density. However, Si-based anodes are subjected to a limited electrochemical cycling lifetime due to their large volume change. Herein, a honeycomb-like biomass-derived carbon nanosheet framework is reported to encapsulate Si nanoparticles via a facile molten salt templating method. The carbon framework provides sufficient void space for effectively accommodating the large volume expansion of Si upon Li+ insertion. Moreover, the interconnected carbon skeletons afford fast electron/ion transport pathways for improving the reaction kinetics. Consequently, the porous Si/carbon composite could exhibit a high and stable Li storage capacity of 1022 mAh g−1 at 0.2 A g−1 over 100 cycles along with superior rate capability (555 mAh g−1 at 5 A g−1). This study demonstrates an effective structural design strategy for Si-based anodes toward stable lithium energy storage.  相似文献   

14.
Si nanoparticle (Si‐NP) composite anode with high rate and long cycle life is an attractive anode material for lithium‐ion battery (LIB) in hybrid electric vehicle (HEV)/pure electric vehicle (PEV). In this work, a carbon nanotube (CNT)/reduced graphene oxide (rGO)/Si nanoparticle composite with alternated structure as Li‐ion battery anode is prepared. In this structure, rGO completely wraps the entire Si/CNT networks by different layers and CNT networks provide fast electron transport pathways with reduced solid‐state diffusion, so that the stable solid‐electrolyte interphase layer can form on the whole surface of the matrix instead of on single Si nanoparticle, which ensure the high cycle stability to achieve the excellent cycle performance. As a result, the CNT/rGO/Si‐NP anode exhibits high performances with long cycle life (≈455 mAh g?1 at 15 A g?1 after 2000 cycles), high specific charge capacity (≈2250 mAh g?1 at 0.2 A g?1, ≈650 mAh g?1 at 15 A g?1), and fast charge/discharge rates (up to 16 A g?1). This nanostructure anode with facile and low‐cost synthesis method, as well as excellent electrochemical performances, makes it attractive for the long life cycles at high rate of the next generation LIB applications in HEV/PEV.  相似文献   

15.
In order to improve the rate and reversible capacity of lithium-sulfur (Li-S) battery, a reagent of dithiothreitol (DTT) was utilized to check the dissolution and shuttle of long-chain lithium polysulfides (LiPSs) by cutting the disulfide bond (–S–S– bonds) in them. The slurry of DTT-doped multi-walled carbon nanotubes (MWCNTs) was coated on the surface of sulfur cathode as a shield to slice the long-chain LiPSs to short-chain ones for checking the dissolution and migration of LiPSs to lithium anode. The morphology and structure of the electrodes were observed by scanning electron microscopy (SEM). The electrochemical performance was tested by galvanostatic charge-discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The initial discharge capacity of S-DTT- carbon nanotube paper (CNTP) electrode reached 1670 and 949 mAh/g at 0.05 and 2 C respectively with a coulombic efficiency of over 99%. The electrode maintained a reversible specific capacity of 949 mAh/g after 45 cycles at 2 C. This suggested that the DTT-doped MWCNT coating can restrain shuttle effect and improve the rate and capacity of Li-S battery. The S-DTT-CNTP electrode not only accommodates the volume expansion but also provides stable electronics and ions channels.  相似文献   

16.
A novel unique C@SnS2 core-shell structure composites consisting of well-dispersity carbon microspheres and ultrathin tin disulfide nanosheets were successfully synthesized for the first time through a simple solvothermal method. The thin SnS2 nanosheets grew onto the carbon microspheres surfaces perpendicularly and formed the close-knit porous structure. When it was used as anode materials for lithium-ion batteries, the hybrid C@SnS2 core-shell structure composites showed a remarkable electrochemical property than pure SnS2 nanosheets. Typically, the hybrid composites with SnS2 nanosheet shells and carbon microsphere’s core exhibited an excellent initial discharge capacity of 1611.6 mAh/g. Moreover, the hybrid composites exhibited capacities of 474.8–691.6 mAh/g at 100 mA/g over 50 battery cycles, while the pure SnS2 could deliver capacities of 243–517.6 mAh/g in the tests. The results indicated that the improvement of lithium storage performance of the core-shell structure C@SnS2 anode materials in terms of rate capability and cycling reversibility owing to the introduction of the smooth carbon microspheres and special designing of core-shell structure.  相似文献   

17.
Graphene‐based phosphorus‐doped carbon (GPC) is prepared through a facile and scalable thermal annealing method by triphenylphosphine and graphite oxide as precursor. The P atoms are successfully doped into few layer graphene with two forms of P–O and P–C bands. The GPC used as anode material for Na‐ion batteries delivers a high charge capacity 284.8 mAh g?1 at a current density of 50 mA g?1 after 60 cycles. Superior cycling performance is also shown at high charge?discharge rate: a stable charge capacity 145.6 mAh g?1 can be achieved at the current density of 500 mA g?1 after 600 cycles. The result demonstrates that the GPC electrode exhibits good electrochemical performance (higher reversible charge capacity, super rate capability, and long‐term cycling stability). The excellent electrochemical performance originated from the large interlayer distance, large amount of defects, vacancies, and active site caused by P atoms doping. The relationship of P atoms doping amount with the Na storage properties is also discussed. This superior sodium storage performance of GPC makes it as a promising alternative anode material for sodium‐ion batteries.  相似文献   

18.
The cathode materials, pristine Li2MnSiO4 and carbon-coated Li2MnSiO4 (Li2MnSiO4/C), were synthesized by the sol–gel method. Power X-ray diffraction and scanning electron microscopy analyses show that the presence of carbon during synthesis can weaken the formation of impurities in the final product and decrease the particle size of the final product. The effects of carbon coating on electrochemical characteristics were investigated by galvanostatic cycling test and electrochemical impedance spectroscopy. The galvanostatic cycling test results indicate that Li2MnSiO4/C cathode exhibits better electrochemical performance with an initial discharge capacity of 134.4 mAh g−1 and a capacity retention of 63.9 mAh g−1 after 20 cycles. Electrochemical impedance analyses confirm that carbon coating can increase electronic conductivity, which results in good electrochemical performance of Li2MnSiO4/C cathode. The two semicircles and the large arc obtained in this study can be attributed to the migration of lithium ions through the solid electrolyte interphase films, the electronic properties of the material, and the charge transfer step, respectively.  相似文献   

19.
SiO2 is one of the most promising lithium storage materials for lithium-ion batteries anodes due to its low cost, good environmental compatibility, low working voltage, and high-specific capacity. In this work, the desert sands, which are rich in SiO2, are investigated as the anode material for lithium-ion batteries. The electrochemical activation, lithium storage capacity, and cycle properties are highly dependent on the particle size distribution of sands. As the average particle sizes of sands gradually decrease, the reversible lithium storage capacity increases from 137 mAh g?1 (several microns) to 492 mAh g?1 (several submicrons). The 72 h-milled sands (average particle size: ~1 μm) deliver a stable lithium storage capacity of ~400 mAh g?1 over 400 cycles with the capacity retention as high as 95%. The reason for the electrochemical activation, lithium storage capacity, and cycle properties of sands associated with their particle size distribution is also discussed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号