二氧化锡/碳气凝胶的制备与电化学性能研究

应用真空浸渍法制备二氧化锡/碳气凝胶的复合材料. XRD、BET、SEM及TEM等测试结果显示,二氧化锡纳米颗粒（5~10 nm）均匀地填充在碳气凝胶的孔道内部. 在100 mA/g的电流密度下经过100周次充放电测试,该材料的容量保持率为首次循环的61.9%.     

CoO纳米颗粒/石墨烯纳米纤维复合材料的制备及电化学性能

用石墨烯和Co(CH₃COO)₂·4H₂O作为原料,利用超声辅助法合成了锂离子电池的负极材料CoO纳米颗粒/中空石墨烯纳米纤维复合物.采用X射线衍射(XRD)确定材料的物相组成,采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)观察材料的表面形貌和微观结构,采用X射线光电子能谱(XPS)确定材料的价态结构.采用循环伏安、恒电流充放电和交流阻抗谱表征材料的电化学性能.结果显示,在100 mA/g的电流密度下,循环了160次后,可逆容量仍超过800 mA/g,库仑效率保持在99%以上.该材料优异的电化学性能主要归因于石墨烯的中空纤维结构,中空内部可以容纳电解液,能直接将离子输送到颗粒表面,实现了离子的快速传输;二维中空纤维搭建成三维网络结构,实现了三维电子传导网络.     

WO_3纳米棒/石墨烯复合材料的制备及电化学储锂性能

以氯化钨和氧化石墨烯(GO)为原料,乙醇为溶剂,一步合成了WO3纳米棒/石墨烯纳米复合材料(WO3/RGO).将WO3/RGO纳米复合材料用于锂离子电池负极,并通过充放电测试、循环伏安(CV)和电化学阻抗谱(EIS)技术综合考察了该材料的储锂性能.结果显示,在0.1C(1C=638 mA?g-1)倍率下,复合物的首次放电比容量达到761.4 mAh?g-1,100次循环后可逆容量仍保持在635 mAh?g-1,保持率为83.4%.即使在5C倍率下容量仍高达460 mAh?g-1.由此说明,WO3/RGO纳米复合物具有优异的循环稳定性及倍率性能,可望用于高性能锂离子电池.     

介孔碳-二氧化钛纳米复合材料的制备及其电化学应用

通过多巴胺的原位聚合,将聚多巴胺(PDA)均匀包裹在钛纳米管(TNTs)表面,再在氮气保护下经过高温灼烧,制备得到介孔碳-二氧化钛(MC-TiO_2)纳米复合材料,进一步采用氢氟酸(HF)对该复合材料进行处理可调控其中二氧化钛的含量。将HF处理前后的复合材料分别制成锂离子电池的负电极。采用透射电镜(TEM)、扫描电镜(SEM)、氮气吸附测试、X射线衍射(XRD)、热重分析(TG)等多种测试手段对复合材料进行了表征。研究结果表明:由这两种电极构成的锂电池均有较好的充-放电效率和循环稳定性;未经HF处理的复合材料(MC-TiO_2)作负极的电池的电容量较低(约130 mA·h/g),而经HF处理的复合材料(MC-TiO_2)_a作负电极的电池的电容量有显著提升,首次放电容量达到1 100 mA·h/g,之后的59次循环中放电容量稳定在360mA·h/g。     

碳包覆氟化亚铁纳米复合材料的制备及电化学性能

通过高温热分解法制备了碳包覆氟化亚铁纳米复合材料(FeF₂/C), 并对其结构、 形貌及电化学性能进行了研究. 结果表明, 该方法对FeF₂实现了碳包覆, 且形成部分碳化铁(Fe₃C). 电化学性能测试结果表明, 该材料在0.1C倍率下循环100周后的放电比容量达到246.7 mA·h/g, 相比于第2周的容量保持率高达93.6%, 具有良好的循环稳定性.     

MoO_3纳米带/RGO复合材料的制备及其电化学性能研究

以水杨酸为模板剂和还原剂,采用水热法制备得到了一种MoO3纳米带/RGO复合材料。利用XRD、SEM、TEM、拉曼光谱、恒流充放电、交流阻抗等手段对样品的结构、形貌以及电化学性能进行表征。测试结果表明,MoO3纳米带/RGO复合材料作为锂离子电池负极材料,在50 m A·g-1的电流密度下可逆比容量为1 000 m Ah·g-1,循环50次后比容量还保持在950 m Ah·g-1,相比于MoO3纳米带其容量保持能力和循环性能得到了显著改善。     

锂离子电池Si@void@C复合材料的制备及其电化学性能

以纳米Si颗粒为核心,正硅酸四乙酯(TEOS)为SiO_2源,采用Stober法在Si表面包覆一层SiO_2,再以多巴胺为碳源,通过碳化处理将SiO_2表面的聚多巴胺层转化成碳层。最后,用HF刻蚀SiO_2并留下空隙,得到Si@void@C复合纳米颗粒。利用X射线衍射、扫描电镜、透射电镜和恒流充放电测试对材料的物相、微观形貌和电化学性能进行表征。结果表明,在0.1 A·g~(-1)电流密度下,Si@void@C负极材料充放电循环100次后充电比容量仍然有1 319.5 mAh·g~(-1),容量保持率为78.4%,表现出优异的电化学性能。     

锂离子电池Si@void@C复合材料的制备及其电化学性能

以纳米Si颗粒为核心,正硅酸四乙酯（TEOS）为SiO₂源,采用Stober法在Si表面包覆一层SiO₂,再以多巴胺为碳源,通过碳化处理将SiO₂表面的聚多巴胺层转化成碳层。最后,用HF刻蚀SiO₂并留下空隙,得到Si@void@C复合纳米颗粒。利用X射线衍射、扫描电镜、透射电镜和恒流充放电测试对材料的物相、微观形貌和电化学性能进行表征。结果表明,在0.1 A·g^-1电流密度下,Si@void@C负极材料充放电循环100次后充电比容量仍然有1 319.5 mAh·g^-1,容量保持率为78.4%,表现出优异的电化学性能。     

TiO2@MWNTs纳米复合材料的制备及其储锂性能

以TiOSO4为钛源,多壁碳纳米管(MWNTs)为载体,溶剂热法制备了多壁碳纳米管/二氧化钛纳米复合材料(TiO2@MWNTs),并利用XRD,SEM,TEM,N2吸附-脱附和TG-DSC等测试手段对合成产物的结构和形貌进行表征,用恒流充放电测试研究TiO2@MWNTs纳米复合材料的储锂性能.N2吸附-脱附曲线和孔径分布曲线证实TiO2@MWNTs存在多级孔道结构以及较大的比表面积.电化学测试结果表明,与纯TiO2颗粒相比,TiO2@MWNTs纳米复合材料具有更好的容量保持率和倍率性能.在1 C倍率下,复合材料的可逆容量为200 mAh?g-1,循环100圈后容量仍达182 mAh?g-1,即使在10 C大倍率下,容量约为100 mAh?g-1左右.     

PAni/Si/G/C复合材料的制备及电化学性能

通过球磨及高温固相法制得了Si/C复合材料,并氧化合成聚苯胺包覆于硅碳复合材料的表面. 采用XRD、SEM、红外和热重分析观察复合材料形貌、分析样品结构,循环伏安法和充放电测试表征PAni/Si/G/C电极电化学性能. 结果表明,PAni/Si/C复合材料表面覆盖了较为完整的片层状结构的聚苯胺膜,可逆容量高达784 mAh.g^-1,50次周期循环后,嵌锂容量保持在690 mAh?g-1.     

多壁纳米碳管约束二硫化锡作为锂离子电池负极的电化学行为

通过两步法制备多壁纳米碳管约束SnS_2纳米材料(SnS_2@MWCNT)。采用直流电弧等离子体法在甲烷气氛下制备多壁纳米碳管约束金属锡纳米结构(Sn@MWCNT)作为前驱体,再通过硫化反应获得SnS_2@MWCNT纳米结构。对材料进行Raman、X射线衍射(XRD)、透射电镜(TEM)等物理表征的结果显示多壁纳米碳管长约400nm,表面碳层晶化程度良好,碳层厚度约10 nm。以Sn S2@MWCNT纳米结构作为负极材料的锂离子电池显示出较为良好的电化学性能。其首次充放电库伦效率为71%,循环50次后,容量仍保持703 mAh?g~(-1)。SnS_2@MWCNT纳米结构电极的高容量特性源于多种活性物质共同提供容量,且各物质反应平台不同。平台呈现明显阶梯型,缓解了体积膨胀效应对电极材料的破坏。     

锂离子电池高比容量FeSn_2-C复合负极材料的合成与性能

Sn基合金负极材料具有高达990 mAh·g-1的理论比容量,但其也存在因脱嵌锂过程发生巨大的体积变化而导致循环性能较差的问题.本文以Sn、Fe、石墨为原料利用简易的高能球磨法成功制备了具有核壳结构的FeSn2-C复合物,系统研究了球磨时间、FeSn2相含量对材料物相结构及电化学性能的影响,并分析了电极的失效机理.研究表明,球磨时间的增加有利于FeSn2金属间化合物相的形成及材料颗粒的细化,进而有利于材料比容量的增加及循环性能的提升;FeSn2相含量的增加能够提高FeSn2-C材料的比容量,但会降低FeSn2-C电极的循环稳定性.经工艺优化及组分调节,球磨24 h合成的Sn20Fe10C70材料具有最优的电化学性能,材料的比容量在540mAh·g-1左右,并能稳定循环100次,是一种非常有发展前途的锂离子电池高比容量负极材料.     

锂离子电池高比容量FeSn2-C复合负极材料的合成与性能

Sn基合金负极材料具有高达990 mAh·g^-1的理论比容量,但其也存在因脱嵌锂过程发生巨大的体积变化而导致循环性能较差的问题. 本文以Sn、Fe、石墨为原料利用简易的高能球磨法成功制备了具有核壳结构的FeSn₂-C复合物,系统研究了球磨时间、FeSn₂相含量对材料物相结构及电化学性能的影响,并分析了电极的失效机理. 研究表明,球磨时间的增加有利于FeSn₂金属间化合物相的形成及材料颗粒的细化,进而有利于材料比容量的增加及循环性能的提升;FeSn₂相含量的增加能够提高FeSn₂-C材料的比容量,但会降低FeSn₂-C电极的循环稳定性. 经工艺优化及组分调节,球磨24 h合成的Sn₂₀Fe₁₀C₇₀材料具有最优的电化学性能,材料的比容量在540 mAh·g^-1左右,并能稳定循环100次,是一种非常有发展前途的锂离子电池高比容量负极材料.     

A Low-Cost and Scalable Carbon Coated SiO-Based Anode Material for Lithium-Ion Batteries

Silicon monoxide (SiO) is considered as one of the most promising alternative anode materials thanks to its high theoretical capacity, satisfying operating voltage and low cost. However, huge volume change, poor electrical conductivity, and poor cycle performance of SiO dramatically hindered its commercial application. In this work, we report an affordable and simple way for manufacturing carbon-coated SiO−C composites with good electrochemical performance on kilogram scales. Industrial grade SiO was modified by carbon coating using cheap and environment friendly polyvinyl pyrrolidone (PVP) as carbon source. High-resolution transmission electron microscopy (HRTEM) and Raman spectra results show that there is an amorphous carbon coating layer with a thickness of about 40 nm on the surface of SiO. The synthesized SiO−C-650 composite shows great electrochemical performance with a high capacity of 1491 mAh.g⁻¹ at 0.1 C rate and outstanding capacity retention of 67.2 % after 100 cycles. The material also displays an excellent performance with a capacity of 1100 mAh.g⁻¹ at 0.5 C rate. Electrochemical impedance spectroscopy (EIS) results also prove that the carbon coating layer can effectively improve the conductivity of the composite and thus enhance the cycling stability of SiO electrode.     

锂离子电池锡薄膜负极制备及电化学性能研究

应用真空蒸发法在泡沫铜基底上制备锡薄膜负极.XRD、SEM分析表征薄膜的物相结构及其微观形貌,并测试了材料的电化学性能.结果表明,泡沫铜基底的三维结构增强了活性物质与基底的结合力.在同一基底温度下,锡颗粒随蒸发时间延长逐渐增大,电池电化学性能降低;而在同一时间内,升高基底温度,颗粒无明显变化,电池循环寿命有了很大提高.样品A″电池(基底温度:200℃,蒸发时间:0.5 h)经100次充放电循环后比容量仍达407.3 mAh·g-1.     

功率型锂离子电池负极材料TiO2/石墨烯的制备及其电化学性能研究

采用无表面活性剂回流法制备了蜂窝状TiO2/石墨烯(GNs)复合材料.扫描电子显微镜(SEM)及透射电子显微镜(TEM)表征结果表明,TiO2颗粒约5～10 nm,均匀地分散在石墨烯的表面.锂电池测试显示,1C充电容量稳定在240.1 mAh.g-1;30C充电容量为169.5 mAh.g-1;当电流调回1C时,其充电容量仍可完全恢复(241.7 mAh.g-1);10C 300周期循环电极容量保持率为89.8%.     

Novel Biomass-derived Hollow Carbons as Anode Materials for Lithium-ion Batteries

A novel hollow carbon derived from biomass lotus-root has been prepared by a one-step carbonization method. The carbon anode obtained at 900 ℃ showed the best electrochemical performance, corresponding to a high specific capacity of 445 mA∙h/g at 0.1 C, as well as excellent cycling stability after 500 cycles. Further investigation exhibits that the lithium storage of hollow carbon involves Li⁺ adsorption in the defect sites and Li⁺ insertion. The results showed that the intrinsic structure of lotus root can inspire us to prepare biomass carbon with a hollow structure as an excellent anode for lithium-ion batteries.     

NaTiSi2O6/C复合材料用于锂离子电池负极材料

The development of human society and the continuously emerging environmental problems call for cleaner energy resources. Lithium-ion batteries, since their commercialization in the early 1990s, have been an important power source of mobile phones, laptops as well as other portable electronic devices. Their advantages include environment-friendliness, light weight, and no memory effect compared with lead-acid or nickel-cadmium batteries. Electrode materials play an important role in the performance of lithium-ion batteries. The traditional commercial anode material, graphite, has a theoretical specific capacity of 372 mAh·g^-1 and working potential close to 0 V (vs Li⁺/Li), making it prone to the formation of lithium dendrite, which may cause short circuit especially when large current is applied. Another commercial anode material Li₄Ti₅O₁₂, which also undergoes an intercalation reaction during lithiation process, has a theoretical specific capacity of 175 mAh·g^-1 along with three lithium-ion intercalations per formula unit. This is relatively small, and it has a relatively high working potential of 1.55 V (vs Li⁺/Li), which reduces its output voltage and specific energy when assembled in full battery. To overcome the shortcomings mentioned above, it is essential to search for new anode materials that are low-cost, environment-friendly, and easy to synthesize. Silicate materials have gained widespread attention owing to their low cost and facile synthesis. Herein, we report for the first time a novel titanosilicate, NaTiSi₂O₆, synthesized by sol-gel and solid sintering. It is isostructural to pyroxene jadeite NaAlSi₂O₆, belonging to monoclinic crystal system with a space group of C2/c. By in situ pyrolysis and carbonization of glucose, nanosized NaTiSi₂O₆ mixed with carbon was successfully obtained with a specific surface area of 132 m²·g^-1, calculated according to the Brunauer–Emmett–Teller formula. The specific charge/discharge capacity in the first cycle at current density of 0.1 A·g^-1 is 266.6 mAh·g^-1 and 542.9 mAh·g^-1, respectively, with an initial coulombic efficiency of 49.1%. After 100 cycles, it retains a specific charge capacity of 224.1 mAh·g^-1, corresponding to a capacity retention rate of 84.1%. The average working potential of NaTiSi₂O₆ is 1.2–1.3 V (vs Li⁺/Li), slightly lower than that of Li₄Ti₅O₁₂. The reaction mechanism while charging and discharging was determined by in situ X-ray diffraction test as well as selected area electron diffraction. The results showed that NaTiSi₂O₆ undergoes an intercalation reaction during lithiation process, with two lithium-ion intercalations per formula unit. This makes NaTiSi₂O₆ a new member of the silicate anode material family, and may provide insights into the development of new silicate electrode materials in the future.     

锂离子电池Sn-Co-Zn合金负极材料电沉积及其储锂性能

运用电沉积技术制备出Sn-Co-Zn合金电极材料.采用X射线衍射(XRD)和扫描电子显微镜(SEM)分析了该合金材料的相结构和表面形貌.通过循环伏安和电位阶跃实验研究了Sn-Co-Zn合金的电沉积机理,实验表明,Sn-Co-Zn合金电沉积按扩散控制连续成核和三维生长方式进行.XRD结果表明,该合金由CoSn3、Co3Sn2和Zn组成.电化学性能测试表明:Sn-Co-Zn合金电极首次放电(脱锂)容量达751mAh·g-1,首次循环的库仑效率为88%;30周循环之后放电容量为510mAh·g-1.该Sn-Co-Zn合金电极良好的电化学储锂性能可能归因于材料的多相结构.