Sn/碳多孔复合材料的制备与储锂性能

通过高温煅烧乙二胺四乙酸二钠和四氯化锡混合物,制备了Sn/碳多孔复合材料。用X射线衍射和扫描电镜对材料的物相组成和形貌进行了表征,用循环伏安和恒流充放电技术测试了材料的储锂性能。结果表明:Sn/碳多孔复合材料呈多层夹心结构,作为锂离子电池负极材料经过100次充放电循环,可逆比容量保持在767 m Ah/g,在1C倍率下容量达到391 m Ah/g。     

介孔锡碳复合微球负极材料的原位合成及锂电性能

以五水四氯化锡为锡源,以间苯二酚和甲醛为碳源,采用简单的水热-碳热还原法对其进行原位合成,通过水解-聚合-原位包覆复合,再经高温碳化后成功制备含有介孔结构的Sn@C复合微球材料。结果表明,该Sn@C复合微球材料直径约为1.5μm,分布在碳基体上的Sn颗粒最小约3nm,最大可达20nm;其比表面积为401m2g~(-1),最可几孔径为3.8nm;其首次放电比容量为1237m Ah g~(-1),循环30次后,比容量为470m Ah g~(-1),经过50m A g~(-1)、100m A g~(-1)、200m A g~(-1)、1000m A g~(-1)大电流密度下各循环10次后,放电比容量仍有255m Ah g~(-1),再次返回到50m A g~(-1)时又增至431m Ah g~(-1)。与以二氧化锡为锡源进行简单混合再碳热还原的锡碳复合材料相比,该Sn@C复合微球材料不仅表现出较高的放电比容量,同时也具有较好的循环稳定性能。     

有机碳源包覆磷酸铁锂正极材料改性研究

以Fe2O3为Fe源、LiH2PO4为Li源和P源、分别以聚乙烯醇(PVA)、淀粉、柠檬酸为碳源,采用液相分散混合、雾化造粒及高温固相处理工艺制备得到碳包覆的磷酸铁锂正极材料(LiFePO4/C),考察不同有机碳源包覆改性对磷酸铁锂正极材料物理及电化学性能的影响。结果表明:以聚乙烯醇包覆制备的LiFePO4/C材料的首次放电比容量为153.8 mAh/g,首次效率大于90%,材料物相纯正,颗粒呈类球形均匀分布、无团聚现象;淀粉包覆的样品的比容量稍低,为144.4 mAh/g,柠檬酸包覆的产物的比容量最低,为139.4 mAh/g。     

碳热还原法制备锡-石墨复合材料及其性能表征

用碳热还原法制备了锡-石墨复合材料,通过XRD及SEM、恒流充放电循环、慢速扫描循环伏安和电化学阻抗测试等方法对其电化学嵌脱锂性能进行了研究. 结果表明,SnO2被石墨还原成金属Sn圆球颗粒,球粒平均尺寸4 mm,均匀分散,部分附着在片状石墨上. 该材料的首次嵌、脱锂比容量分别可以达到887和615 mA×h/g,库仑效率为69%,循环15次后的脱锂比容量为387 mA×h/g,高于石墨,容量保持率为63%,平均容量损失率为2.5%/次.     

不同形貌结构SnO_2/C复合材料的可控合成

Sn O2理论上的可逆锂贮存容量为790 m Ah/g,这是当前使用的石墨的理论容量372 m Ah/g的两倍以上,然而其循环性能较差。研究发现,Sn O2和碳基体的复合可以有效的改善其循环性能,文章综述了的不同形貌结构的Sn O2/C复合材料的可控合成,以及分析总结了其形貌对其可逆容量和循环性能的影响。     

碳掺杂改善LiFePO4电化学性能

采用葡萄糖为碳源,通过固相合成法制备了掺碳的LiFePO4正极材料,并对样品的性能进行了研究分析.结果表明,少量的碳掺杂并未改变LiFePO4的晶体结构但显著改善了其电化学性能,LiFePO4/C样品的粒度较小粒径分布均匀,0.1 C首次放电比容量为141.9 mAh/g,循环50次后容量下降11.2 mAh/g,以1 C倍率首次放电比容量为126.5 mAh/g,循环50次后容量保持率为87.2%.     

碳源对碳热法制备LiFePO4/C复合电极材料性能的影响

以廉价的Fe2O3为铁源,(NH4)H2PO4为磷源,Li2CO3为锂源,分别以乙炔黑、葡萄糖、PEG6000为还原剂和碳源,采用碳热还原法制备了LiFePO4/C复合材料。X射线衍射(XRD)分析表明用三种碳源都合成了橄榄石结构的LiFePO4。扫描电子显微镜(SEM)分析显示,以PEG6000为碳源合成的LiFePO4/C复合材料粒径较小,较均匀,且有较好的碳包覆。以充放电曲线、循环性能和交流阻抗等测试研究了材料的电化学性能,结果表明,以PEG6000为碳源合成的材料的电化学性能较好,0.1C、1C下首次放点比容量分别为144.7 mAh/g、132 mAh/g。     

不同碳源对Li_2FeSiO_4/C正极材料电化学性能的影响

以草酸亚铁为铁源,正硅酸四乙酯为硅源,乙酸锂为锂源,葡萄糖、淀粉、柠檬酸和沥青分别为碳源,采用水热辅助溶胶-凝胶法制备了锂离子电池Li_2FeSiO_4/C复合正极材料,考察葡萄糖、淀粉、柠檬酸和沥青分别作为碳源对Li_2FeSiO_4/C电化学性能的影响。研究表明:沥青为碳源制备的Li_2FeSiO_4/C在0.1 C倍率下的首次放电比容量为114.1 m A·h/g,充放电平台相差最小,0.2,0.5,1,2 C倍率下比容量保持得最高,电化学阻抗最小,Li+扩散率最大。     

双碳源制备高性能Na_3V_2(PO_4)_3/C正极材料

以聚丙烯酸和葡萄糖为双碳源,通过碳热还原法制备颗粒分散性良好的Na_3V_2(PO_4)_3/C复合材料。借助聚丙烯酸长链分子对原料前驱体的良好分散性和葡萄糖热解碳的高导电性,获得的Na_3V_2(PO_4)_3/C作为钠离子电池正极材料,表现出高的倍率放电容量和长循环寿命。在5C倍率下循环1000次后放电容量剩余101 m Ah·g~(-1),容量保持率为92.6%。本文的双碳源策略为制备高性能电极材料提供了一个可行的途径。     

焙烧条件对纳/微结构LiFePO4/C性能的影响

以FePO_4·2H_2O、LiOH·H_2O、淀粉为原料,采用湿法球磨-喷雾干燥-碳热还原法制备出纳/微结构LiFePO_4/C复合材料,通过XRD、SEM测定了LiFePO_4/C复合材料的形态结构,考察了焙烧温度、焙烧时间对纳/微结构LiFePO_4/C形态和电化学性能的影响。结果表明:最佳的焙烧温度为650℃、焙烧时间为8.5 h,该条件下所得的LiFePO_4/C复合材料10 C放电比容量为123.0 mA·h/g,100次循环后放电比容量的保持率接近100%。     

Synthesis of confinement structure of Sn/C-C (MWCNTs) composite anode materials for lithium ion battery by carbothermal reduction

A composite anode material was prepared with confined tin into multiwall carbon nanotube by carbothermal reduction. The morphology and structure of Sn/C (nature graphite) and Sn/C-C (nature graphite + multiwall carbon nanotube) were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was revealed that the additive of MWCNT was a crucial factor to improve Sn /C composite anodes for cyclability and reversible capacity. Volume changes and morphological changes in Sn can be reduced by encasing MWCNT in a carbonaceous material that has sufficient flexibility to act as a buffer. Electrochemical performance test shows that the charge capacity of the Sn/C-C (NG + MWCNT) electrode in the fiftieth cycle was 400 mAh/g, which was higher than that of the Sn/C (NG) electrode. After 50 cycles, the retention of the Sn/C-C electrode and the Sn/C electrode was 80% and 63%, respectively.     

Electrochemical performance of Sn film reinforced by Cu nanowire

Sn/Cu nanowire composite film was electrodeposited on copper foil substrates and used as an anode material for lithium-ion batteries. The structure of the obtained composite film anode was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performance was evaluated by cyclic voltammetry, galvanostatic cycling and impedance spectroscopy. It was found that the Sn/Cu nanowire composite film anode showed a better cycle stability than Sn film anode, whereas the Sn/CNT composite film anode indicated poor capacity retention. It could be deduced that copper nanowire reinforced the Sn film anode due to the better wetting property of Sn on the surface of copper and reduced the loss of electric contact among tin particles in the Sn/Cu nanowire composite film anode.     

用于锂离子电池负极SnO2MCMB复合材料的研究

以中间相碳微球(MCMB)为核心,用直接沉淀法制备了一种氧化锡颗粒修饰的新型复合碳材料.用X射线衍射和扫描电镜对材料的结构及形貌进行了表征.通过恒流充放电、交流阻抗、循环伏安等测试手段对该材料的嵌脱锂特性进行了研究,循环20周后其比容量仍然保持在360 mAh/g以上.此种复合物可以作为一种锂离子电池新型负极材料.     

Electrochemical properties of nanosize Sn-coated graphite anodes in lithium-ion cells

A series of Sn-coated graphite composite materials for lithium-ion batteries were prepared by microencapsulating nanosize Sn particles in graphite. The nanosize Sn particles are homogeneously dispersed in the graphite matrix via electroless chemical reduction. The tin-graphite composite showed a great improvement in lithium storage capacity. Since Sn is an active element to lithium, Sn can react with lithium to form Li_4.4Sn alloys, a reaction accompanied by a dramatic volume increase, whereas the ductile graphite matrix provides a perfect buffer layer to absorb this volume expansion. Therefore, the integrity of the composite electrode is preserved during lithium insertion and extraction. Cyclic voltammetry was employed to identify the reaction process involved in lithium insertion and extraction in the graphite structure, as well as lithium alloying with tin. The tin-graphite composites provide a new type of anode material for lithium-ion batteries with an increased capacity.     

Advanced Sn/C composite anodes for lithium ion batteries

Metallic tin was deposited in fine particulate form on the surface of carbonaceous mesophase spherules (CMS) and in the pores of porous carbon by the decomposition and reduction of tin(II) 2-ethylhexanoate at 450 °C. The Sn/C composite powders obtained were used as anode materials for lithium ion cells. Electrochemical cycling tests of coin cells show that the dispersion of tin into the carbonaceous materials enhances the reversible capacity of the electrodes. The capacity retention at the 50th cycle is 91 % for Sn/CMS composite containing 22% tin, against 428 mAh g^–1 at the first cycle. With further increase in tin content, the capacity fade upon cycling is more rapid.     

Nanostructured Sn–Ti–C composite anodes for lithium ion batteries

Nanostructured Sn–Ti–C composites have been synthesized by a facile, inexpensive high energy mechanical milling process and investigated as an anode material for lithium-ion cells. Characterization data collected with X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) reveal an uniform dispersion of Sn nanoparticles within the conductive, amorphous (or poorly crystalline) TiC + C matrix. Among the three Sn–Ti–C compositions investigated, the Sn₁₁Ti₃₁C₅₈ composite exhibits the best electrochemical performance, with a capacity of ∼370 mAh/g and excellent capacity retention over 300 cycles studied. It also exhibits excellent cycle life with LiMn₂O₄ spinel cathode, suggesting a tolerance of the Sn–Ti–C anodes toward poisoning by the manganese leached out from the spinel cathode. The superior electrochemical performance of Sn₁₁Ti₃₁C₅₈ composite is attributed to a homogeneous distribution of the electrochemically active amorphous Sn, suppression of Sn grain growth, and the mechanical buffering effect provided by the conductive TiC + C matrix toward the volume expansion-contraction occurring during cycling.     

锂离子电池锡/碳复合负极材料的制备及电化学性能研究

以二氧化锡和导电碳(Super P)为原料,通过高能球磨,采用高温固相法制得锡/碳复合材料作为锂离子电池负极材料。用XRD、SEM进行表征,并进行有关电化学性能测试,首次放电比容量高达566.4 mAh.g-1,循环性能得到了较大改善。     

水热法合成球状锡酸镧及其阻燃聚氯乙烯的研究

采用水热法,以锡酸钠和硝酸镧为原料,用氢氧化钠溶液调节pH分别为9、10和11,成功制备了不同粒径的类球状锡酸镧颗粒;对比研究了上述3种粒径尺寸的锡酸镧对聚氯乙烯（PVC）的阻燃和拉伸性能的影响,并采用对纯PVC 和综合性能最好的阻燃样品的残炭进行了分析。结果表明,pH=9时制备的锡酸镧阻燃PVC具有最好的阻燃和拉伸性能;当其添加量为5 g/100 g PVC时,阻燃PVC的极限氧指数为30.8 %,拉伸性能略高于纯PVC,燃烧后形成了带有封闭气孔的致密炭层。     

机械力化学制备锡酸锌及其在PVC中的阻燃应用

以二氧化锡（SnO₂）和氧化锌（ZnO）为原料,通过机械力化学湿法球磨,制备了锡酸锌（ZS）,再与水滑石按一定比例研磨得到锡酸锌改性的水滑石（ZS/HT）。通过扫描电子显微镜、X射线衍射、透射电子显微镜对合成的ZS与ZS/HT做了表征。将制得的ZS/HT应用于PVC制得阻燃PVC样品,当加入10%（ZS与水滑石的质量比）ZS/HT时材料的极限氧指数比纯PVC样品高3.5%,同时材料的力学性能有所增加。热重分析结果表明,ZS/HT的加入促使PVC提前分解成炭,有效提高PVC材料的残炭量。