Li4Ti4.95Al0.05O12/C复合负极材料的制备及电性能研究

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董红玉, 张治军, 尹艳红, 杨书廷. Li₄Ti_4.95Al_0.05O₁₂/C复合负极材料的制备及电性能研究 . 无机材料学报, 2012, 27(12): 1251-1255
DONG Hong-Yu, ZHANG Zhi-Jun, YIN Yan-Hong, YANG Shu-Ting. Preparation and Electrochemical Performance of Li₄Ti_4.95Al_0.05O₁₂/C Anode Materials . Journal of Inorganic Materials, 2012, 27(12): 1251-1255 复制到剪切板

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Li₄Ti_4.95Al_0.05O₁₂/C复合负极材料的制备及电性能研究

董红玉^1,^2,³, 张治军¹, 尹艳红^2,³, 杨书廷^2,³

1. 河南大学特种功能材料教育部重点实验室, 开封475004

2. 河南师范大学化学与化工学院, 新乡453007

3. 河南省动力电池及关键材料工程技术研究中心, 新乡453007

张治军, 教授. E-mail:zzj66@yahoo.com; 杨书廷, 教授. E-mail:yangshuting17@163.com

董红玉(1979-), 女, 博士研究生. E-mail:hongyudong9@foxmail.com

基金:国家自然科学基金(21001041);

摘要

Li₄Ti₅O₁₂是具有良好应用前景的锂离子电池负极材料之一. 本研究以聚丙烯酰胺(PAM)为模板剂和碳源, 采用改进的固相合成法制备锂离子电池负极材料Li₄Ti_4.95Al_0.05O₁₂和Li₄Ti_4.95Al_0.05O₁₂/C. 利用X射线衍射仪、场发射扫描电镜等测试手段表征材料的物相结构和形貌. 结果表明: Al掺杂未改变Li₄Ti₅O₁₂的尖晶石结构, 合成过程中PAM模板剂的引入能够有效调控材料微观形貌并降低颗粒团聚程度. 采用恒流充放电和交流阻抗测试材料的电化学性能, Li₄Ti_4.95Al_0.05O₁₂/C复合材料的比容量和循环性能得到明显改善, 0.2C倍率下首次充放电比容量分别达到159.2和160.8 mAh/g, 5C倍率时仍有较好的循环性能.

关键词: Li₄Ti₅O₁₂; 掺杂; 电性能; 交流阻抗

中图分类号:TQ912 文献标志码:A 文章编号:1000-324X(2012)12-1251-05

Preparation and Electrochemical Performance of Li₄Ti_4.95Al_0.05O₁₂/C Anode Materials

DONG Hong-Yu^1,^2,³, ZHANG Zhi-Jun¹, YIN Yan-Hong^2,³, YANG Shu-Ting^2,³

1. Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004, China

2.School of Chemistry and Enginearing, Henan Normal University, Xinxiang 453007, China

3. Henan Engineering Research Center of Motive Power and Key Materials, Xinxiang 453007, China

Fund:National Natural Science Foundation of China(21001041);

Abstract

Li₄Ti₅O₁₂ is a promising anode electrode material in Lithium ion batteries. Using polyacrylamide as template and carbon source, spinel Li₄Ti_4.95Al_0.05O₁₂and Li₄Ti_4.95Al_0.05O₁₂/C were successfully synthesized by modified solid state method. The results of X-ray diffraction (XRD) and Field-emission scanning electron microscopy show that highly crystalline Li₄Ti_4.95Al_0.05O₁₂and Li₄Ti_4.95Al_0.05O₁₂/C materials without any impurity are obtained. The shape and size of particles are modified by polyacrylamide. The electrochemical performances of materials are investigated in the range of 1.0-2.5 V. The Li₄Ti_4.95Al_0.05O₁₂/C presents a higher specific capacity and better cycling stability than Li₄Ti_4.95Al_0.05O₁₂. The charge and discharge specific capacity of Li₄Ti_4.95Al_0.05O₁₂/C material are 159.2 and 160.8 mAh/g at 0.2C rate.

Keyword: Li₄Ti₅O₁₂; doping; electrochemical performance; AC impedance

Show Figures

电子设备向小型化和微型化方向发展, 锂离子电池的研究和应用越来越得到重视^{[ 1, 2, 3]}. 随着电动汽车的发展, 高功率型的电池成为锂离子电池研究的热点^{[ 4, 5, 6, 7]}. 尖晶石型钛酸锂Li₄Ti₅O₁₂材料在脱嵌锂过程中体积变化率小于1%, 被称为“零形变”材料, 具有好的循环性能. Li₄Ti₅O₁₂材料脱嵌锂电位为1.55 V( vs Li⁺/Li), 能够避免生成锂枝晶, 安全性高并且价格低廉, 是很有潜力的动力型锂离子电池负极材料^{[ 8, 9, 10, 11]}.

尽管Li₄Ti₅O₁₂材料具有诸多优点, 但是由于Li₄Ti₅O₁₂材料的电子结构中本征电导率很低, 影响其电化学性能, 限制了材料的应用^{[ 7]}. 因此, 必须改善Li₄Ti₅O₁₂材料的电化学性能. 通常通过制备纳米Li₄Ti₅O₁₂、表面包覆Ag或C、在Li位和Ti位体相掺杂Nb, Zr, Al, 和Li等方法改善Li₄Ti₅O₁₂材料的电导率^{[ 2, 5, 6, 12, 13, 14, 15, 16, 17, 18, 19]}. 其中Al体相掺杂钛酸锂材料, 能提高材料的本征电导率, 减小材料本身的电阻. 聚丙烯酰胺(PAM)作为模板剂可以调控材料的形貌, 同时其在氮气气氛下产生的裂解碳可以改善材料的导电性能^{[ 20]}, 然而, 采用PAM作为模板剂及碳源合成Li₄Ti_4.95Al_0.05O₁₂/C负极材料尚未见报道. 本工作选择聚丙烯酰胺作为模板剂和碳源并掺杂Al对Li₄Ti₅O₁₂材料进行协同改性, 用改进的固相合成方法制备Li₄Ti_4.95Al_0.05O₁₂/C复合材料, 改善Li₄Ti₅O₁₂材料的电化学性能, 为其大规模应用奠定了基础.

1 实验

1.1 Li₄Ti_4.95Al_0.05O₁₂/C材料的制备

将锐钛矿型TiO₂、LiOH·H₂O和Al(NO₃)₃·9H₂O按照4.95:4.12:0.05比例混合得到混合物1, 然后称取适量聚丙烯酰胺(TiO₂和LiOH·H₂O总质量的8%), 溶解到去离子水中, 得溶液2. 将混合物1加入溶液2中, 在球磨罐中球磨6 h后, 转移到鼓风干燥箱中, 80℃烘干, 于800℃空气中烧结8 h, 随炉温冷却, 得到样品P-Li₄Ti_4.95Al_0.05O₁₂, 标记为样品a. 采用同样的方法, 在N₂气氛保护下800℃烧结8 h, 得到P-Li₄Ti_4.95Al_0.05O₁₂/C复合材料, 标记为样品b.

为了便于比较, 以锐钛矿型TiO₂、LiOH·H₂O和Al(NO₃)₃·9H₂O为反应物, 按4.95:4.12:0.05比例混合均匀后, 空气气氛下800℃保温8 h, 制备G-Li₄Ti_4.95Al_0.05O₁₂作为对比, 标记为样品c.

1.2 电极制备

按质量比80: 10: 10称取电极活性物质、乙炔黑和聚偏二氟乙烯, 混合均匀后, 加入N-甲基-2-吡咯烷酮(NMP)溶剂, 调成浆状, 然后均匀涂覆在铜箔(0.02 mm)上, 真空干燥箱中100℃干燥12 h, 6 MPa压力下压片, 作为工作电极. 以金属锂片作为对电极及参比电极, 隔膜选用Celgard 2400, 电解液为 1 mol/L的LiPF₆ (DMC:EC = 1:1)溶液, 在充满氩气的手套箱(湿度<1×10^-6)中组装CR2032型纽扣电池.

1.3 分析表征和性能测试

采用德国布鲁克AXS公司生产的D8X射线衍射仪对材料的微观结构进行分析, 管压40 kV, 管流20 mA, 扫速0.05º/s, Cu靶Kα射线( λ＝0.15406 nm)入射; 通过德国ZEISS公司场发射SIGMA型扫描电镜观察材料的微观形貌, 加速电压15 kV; 样品的比表积用JW-004BET分析测试仪测定; 用LAND电池测试系统(武汉金诺电子有限公司)对电池进行恒流充放电测试. 充电终止电压为2.5 V, 放电终止电压为1.0 V. 采用上海辰华CHI660B电化学工作站测试材料的电化学交流阻抗, 频率范围是0.01 Hz~ 100 kHz.

2 结果讨论

2.1 结构分析

P-Li₄Ti_4.95Al_0.05O₁₂、P-Li₄Ti_4.95Al_0.05O₁₂/C和G-Li₄Ti_4.95Al_0.05O₁₂材料的晶体结构经X射线粉末衍射仪测定, 结果如图1所示: 三种材料均是尖晶石型结构(JCPDS 26-1198), 没有出现明显的碳或铝化合物的衍射峰. 与纯Li₄Ti₅O₁₂的标准图谱对比, 结果发现, 掺杂Al后的P-Li₄Ti_4.95Al_0.05O₁₂、P-Li₄Ti_4.95Al_0.05O₁₂/C材料, 其 (111)、(311)、(400)、(440)等主要晶面的衍射峰向高角度偏移, PAM作为模板剂在空气条件下制备的P-Li₄Ti_4.95Al_0.05O₁₂样品, 晶胞体积变小, 说明Al进入尖晶石结构, 与文献的结果一致^{[ 15]}. 这是由于半径较小的Al³⁺(0.0535 nm)取代了部分Ti⁴⁺(0.0605 nm), 进入晶格16d位置, 使得晶胞体积变小. 在N₂气氛中制备的Li₄Ti_4.95Al_0.05O₁₂/C复合材料, 与空气气氛下得到的P-Li₄Ti_4.95Al_0.05O₁₂样品相比, 晶胞体积没有明显的变化.

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	图1 样品的XRD图谱Fig. 1 XRD patterns of different samples(a) P-Li₄Ti_4.95Al_0.05O₁₂; (b) P-Li₄Ti_4.95Al_0.05O₁₂/C; (c)G-Li₄Ti_4.95Al_0.05O₁₂

表1 样品的晶胞参数 Table 1 Cell parameters of samples

2.2 形貌分析

图2是样品的FE-SEM照片, 样品(c)是采用固相法制备的Li₄Ti_4.95Al_0.05O₁₂材料, 颗粒表面光滑,呈现不规则的形状, 粒径分布范围较宽, 而且粒径较大, 在1 μm左右. 采用PAM作为模板剂, 在空气气氛中制备的Li₄Ti_4.95Al_0.05O₁₂材料颗粒同样具有光滑的表面, 但是颗粒粒径小于1 μm, 没有棱角, 呈现类球形, 说明PAM模板剂的加入, 能够在材料制备过程中一定程度上调控颗粒的微观形貌及粒径大小. 类球形的颗粒形貌能减小活性材料在制备成电极时颗粒之间的接触电阻, 同时能够改善材料的极板成型性能. 在氮气气氛中制备的Li₄Ti_4.95Al_0.05O₁₂/C复合材料, 颗粒的粒径更小, 而且材料颗粒的表面粗糙, 是由于部分PAM裂解生成的碳包覆在表面, 抑制了晶粒的进一步融合生长. 这说明PAM作为模板剂, 在N₂气氛中能够更好地起到调控材料粒径和形貌的作用, 能够在一定程度上抑制高温烧结过程中材料颗粒的团聚. 同时PAM在裂解时产生的碳包覆在Li₄Ti_4.95Al_0.05O₁₂材料颗粒表面, 能够促进材料颗粒间的良好接触, 从而增加材料的电导率.

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	图2 不同样品的FE-SEM照片Fig. 2 FE-SEM images of different samples(a) P-Li₄Ti_4.95Al_0.05O₁₂;(b) P-Li₄Ti_4.95Al_0.05O₁₂/C; (c) G-Li₄Ti_4.95Al_0.05O₁₂

表2是样品P-Li₄Ti_4.95Al_0.05O₁₂和P-Li₄Ti_4.95Al_0.05O₁₂/C的比表面积和振实密度. 在空气气氛下制备的样品, 比表面积为5.67 m²/g, 采用同样的反应物和反应条件, 在N₂气气氛下制备的Li₄Ti_4.95Al_0.05O₁₂/C复合材料, 具有较大的比表面积, 可达15.70 m²/g, 说明PAM在N₂中裂解生成的碳阻止了材料颗粒的进一步团聚, 这和SEM结果一致. 在电极活性物质与电解液接触时, 材料比表面积的提高使得固液接触面积也得到提高, 这样可以缩短锂离子在固相中的扩散路程以及电子传输路径, 有利于降低活性材料在充放电过程中的极化程度, 因而有利于提高材料的倍率充放电性能^{[ 21]}. 将P-Li₄Ti_4.95Al_0.05O₁₂/C样品在空气气氛中加热至恒重, 利用加热前后样品质量的差值, 计算出样品中碳的含量为4.1%,说明PAM模板剂在N₂气氛中生成了碳.

表2 样品的比表面积和振实密度 Table 2 BET and Tap-density of powders

2.3 电化学性能表征

材料在室温0.2 C倍率1.0~2.5 V电压范围内的充放电性能如图3所示,从图可以看出, G-Li₄Ti_4.95Al_0.05O₁₂材料、P-Li₄Ti_4.95Al_0.05O₁₂材料和P-Li₄Ti_4.95Al_0.05O₁₂/C复合材料的充放电平台均在1.55 V左右, 没有出现其他平台, 说明材料中没有杂相, 与XRD测试结果一致. P-Li₄Ti_4.95Al_0.05O₁₂材料的首次充放电容量分别为150.3和151.8 mAh/g. P-Li₄Ti_4.95Al_0.05O₁₂/C复合材料的首次充放电容量为159.2和160.8 mAh/g. G-Li₄Ti_4.95Al_0.05O₁₂材料的首次充放电容量分别是130.0和133.1 mAh/g. 结果表明, P-Li₄Ti_4.95Al_0.05O₁₂/C复合材料具有较高的脱锂容量.

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	图3 材料在0.2 C倍率的首次充放电曲线Fig. 3 First charge-discharge curves of samples at 0.2 C rate(a) P-Li₄Ti_4.95Al_0.05O₁₂; (b) P-Li₄Ti_4.95Al_0.05O₁₂/C; (c) G-Li₄Ti_4.95Al_0.05O₁₂

图4是材料的倍率循环性能测试结果, 可以看出, G-Li₄Ti_4.95Al_0.05O₁₂材料在0.2 C和5 C进行循环, 容量衰减明显, 而P-Li₄Ti_4.95Al_0.05O₁₂材料和P-Li₄Ti_4.95Al_0.05O₁₂/C复合材料在相同倍率下循环, 均有较好的循环性能, 相比之下, 碳复合材料的高倍率性能更好. 说明裂解碳的存在可以有效降低材料中晶粒及颗粒间的接触电阻、降低充放电过程中的极化程度, 从而改善了钛酸锂材料的倍率性能.

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	图4 在不同充放电倍率下材料的循环性能曲线Fig. 4 Specific capacity dependence on cycle number of samples at different rates(a) P-Li₄Ti_4.95Al_0.05O₁₂; (b) P-Li₄Ti_4.95Al_0.05O₁₂/C; (c) G-Li₄Ti_4.95Al_0.05O₁₂

图5为所制备样品的电化学交流阻抗谱. 图中高中频区的半圆反映的是电荷转移过程的阻抗以及电极和电解液间的界面容抗, 在低频区的直线反映的是锂离子在固体活性材料中扩散所引起的Warburg阻抗^{[ 22, 23, 24]}. Li₄Ti_4.95Al_0.05O₁₂/C材料的电荷转移阻抗明显低于未复合碳的Li₄Ti_4.95Al_0.05O₁₂材料, 反应了掺碳后活性材料插锂过程的快速动力学机制. 说明以PAM为碳源可以有效改善钛酸锂材料的导电性, 有利于提高材料的嵌锂深度, 降低电极活性材料颗粒表面与内部的Li⁺的浓度差, 从而减小电池的极化, 提高放电比容量, 改善电池的倍率性能.

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	图5 样品的交流阻抗图谱Fig. 5 Electrochemical impedance spcetroscopy of samples(a) P-Li₄Ti_4.95Al_0.05O₁₂; (b) P-Li₄Ti_4.95Al_0.05O₁₂/C; (c) G-Li₄Ti_4.95Al_0.05O₁₂

3 结论

采用改进的固相法制备了尖晶石型Li₄Ti_4.95Al_0.05O₁₂材料以及Li₄Ti_4.95Al_0.05O₁₂/C复合材料, 其中以PAM为碳源的Al掺杂钛酸锂材料具有较高的比容量及较好的循环性能和倍率性能, 首次脱锂容量高达159.2 mAh/g. PAM作为模板剂能够一定程度上调控钛酸锂材料的微观形貌和颗粒粒径, 在N₂气氛下, PAM裂解得到的碳可以有效提高材料的导电性能. 此工艺方法简单实用, 使用的材料廉价易得, 便于大规模制备电化学性能优良的负极材料Li₄Ti_4.95Al_0.05O₁₂/C.

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[9]	Wang G J, Gao J, Fu L J, et al. Preparation and characteristic of carbon-coated Li₄Ti₅O₁₂ anode material. Journal of Power Sources, 2007, 174(2): 1109-1112. [本文引用:1] [JCR: 4.675]
[10]	Gao J, Jiang C, Ying J, et al. Preparation and characterization of high-density spherical Li₄Ti₅O₁₂ anode material for lithium secondary batteries. Journal of Power Sources, 2006, 155(2): 364-367. [本文引用:1] [JCR: 4.675]
[11]	Wang D, Ding N, Song X H, et al. A simple gel route to synthesize nano-Li₄Ti₅O₁₂ as a high-performance anode material for Li-ion batteries. Journal of Materials Science, 2008, 44(1): 198-203. [本文引用:1] [JCR: 2.163]
[12]	Huang S, Wen Z, Zhang J, et al. Improving the electrochemical performance of Li₄Ti₅O₁₂/Ag composite by an electroless deposition method. Electrochimica Acta, 2007, 52(11): 3704-3708. [本文引用:1] [JCR: 3.777]
[13]	Huang S, Wen Z, Zhang J, et al. Li₄Ti₅O₁₂/Ag composite as electrode materials for lithium-ion battery. Solid State Ionics, 2006, 177(9/10): 851-855. [本文引用:1] [JCR: 2.046]
[14]	Yang L, Gao L. Li₄Ti₅O₁₂/C composite electrode material synthesized involving conductive carbon precursor for Li-ion battery. Journal of Alloys and Compounds, 2009, 485(1/2): 93-97. [本文引用:1] [JCR: 2.39]
[15]	Wang Z H, Chen G, Xu J, et al. Synthesis and electrochemical performances of Li₄Ti_{4. 95}Al_{0. 05}O₁₂/C as anode material for lithium-ion batteries. Journal of Physics and Chemistry of Solids, 2011, 72(6): 773-778. [本文引用:2] [JCR: 1.527]
[16]	Tian B B, Xiang H F, Zhang L, et al. Effect of Nb-doing on electrochemical stability of Li₄Ti₅O₁₂ discharged to 0 V. Journal of Solid State Electrochemistry, 2012, 16(1): 205-211. [本文引用:1] [JCR: 2.279]
[17]	Gu F, Chen G, Wang Z H. Synthesis and electrochemical performances of Li₄Ti_{4. 95}Zr_{0. 05}O₁₂/C as anode material for lithium-ion batteries. Journal of Solid State Electrochemistry, 2012, 16(1): 375-382. [本文引用:1] [JCR: 2.279]
[18]	Cai R, Yuan T, Ran R, et al. Preparation and re-examination of Li₄Ti_{4. 85}Al_{0. 15}O₁₂ as anode material of lihtium-ion battery. InternationalJournal of Energy Research, 2011, 35: 68-77. [本文引用:1] [JCR: 1.987]
[19]	Cai R, Jiang S M, Yu X, et al. A novel method to enhance rate performance of an Al-doped Li₄Ti₅O₁₂ electrode by post-synthesis treatment in liquid formaldehyde at room temperature. Journal of Materials Chemistry, 2012, 22: 8013-8021. [本文引用:1] [JCR: 5.968]
[20]	Yang S T, Zhao N H, Yin Y H, et al. Synthesis of LiFePO₄/C nano-structure intergrowth by PAM soft templating method. Battery Bimonthly, 2005, 5(4): 263-265. [本文引用:1] [CJCR: 0.568]
[21]	Gao J, Mu X, Li J J, et al. Preparation and characterization of porous spherical Li₄Ti₅O₁₂/C anode material for lithium ion batteries. Journal of Inorganic Materials, 2012, 27(3): 253-257. [本文引用:1] [JCR: 0.531] [CJCR: 1.106]
[22]	Shenouda Atef Y. , Li H. K. Studies on electrochemical behaviour of zinc-doped LiFePO₄ for lithium battery positive electrode. Journal of Alloys and Compounds, 2009, 477(1/2): 498-503. [本文引用:1] [JCR: 2.39]
[23]	Shenouda Atef Y, Li H K. Electrochemical behaviour of tin borophosphate negative electrodes for energy storage systems. Journal of Power Sources, 2008, 185(2): 1386-1391. [本文引用:1] [JCR: 4.675]
[24]	Xiong X H, Wang Z X, Wu L, et al. Effect of Al-doping on structure and eletrochemical performance of Li₄Ti₅O₁₂. The Chinese Journal of Nonferrous Metals, 2011, 21(9): 2146-2150. [本文引用:1] [CJCR: 1.09]

2008

2.046

0.0

... 电子设备向小型化和微型化方向发展, 锂离子电池的研究和应用越来越得到重视^[1,2,3] ...

2004

8.238

0.0

... 电子设备向小型化和微型化方向发展, 锂离子电池的研究和应用越来越得到重视^[1,2,3] ...

... 通常通过制备纳米Li₄Ti₅O₁₂、表面包覆Ag或C、在Li位和Ti位体相掺杂Nb, Zr, Al, 和Li等方法改善Li₄Ti₅O₁₂材料的电导率^{[2, 5,6, 12,13,14,15,16,17,18,19]} ...

2006

0.0

... 电子设备向小型化和微型化方向发展, 锂离子电池的研究和应用越来越得到重视^[1,2,3] ...

2009

4.675

0.0

... 随着电动汽车的发展, 高功率型的电池成为锂离子电池研究的热点^[4,5,6,7] ...

2007

4.675

0.0

... 随着电动汽车的发展, 高功率型的电池成为锂离子电池研究的热点^[4,5,6,7] ...

2008

2.39

0.0

... 随着电动汽车的发展, 高功率型的电池成为锂离子电池研究的热点^[4,5,6,7] ...

2008

3.777

0.0

Electrochimica Acta. 2008, 53(12):4200-4204 DOI:10.1016/j.electacta.2007.12.052

High-rate characteristics of novel anode Li₄Ti₅O₁₂/polyacene materials for Li-ion secondary batteries

Abstract

In recent years, spinel lithium titanate (Li₄Ti₅O₁₂) as a superior anode material for energy storage battery has attracted a great deal of attention because of the excellent Li-ion insertion and extraction reversibility. However, the high-rate characteristics of this material should be improved if it is used as an active material in large batteries. One effective way to achieve this is to prepare electrode materials coated with carbon. A Li₄Ti₅O₁₂/polyacene (PAS) composite were first prepared via an in situ carbonization of phenol–formaldehyde (PF) resin route to form carbon-based composite. The SEM showed that the Li₄Ti₅O₁₂ particles in the composite were more rounded and smaller than the pristine one. The PAS was uniformly dispersed between the Li₄Ti₅O₁₂ particles, which improved the electrical contact between the corresponding Li₄Ti₅O₁₂ particles, and hence the electronic conductivity of composite material. The electronic conductivity of Li₄Ti₅O₁₂/PAS composite is 10⁻¹ S cm⁻¹, which is much higher than 10⁻⁹ S cm⁻¹ of the pristine Li₄Ti₅O₁₂. High specific capacity, especially better high-rate performance was achieved with this Li₄Ti₅O₁₂/PAS electrode material. The initial specific capacity of the sample is 144 mAh/g at 3 C, and it is still 126.2 mAh/g after 200 cycles. By increasing the current density, the sample still maintains excellent cycle performance.

... 随着电动汽车的发展, 高功率型的电池成为锂离子电池研究的热点^[4,5,6,7] ...

... 尽管Li₄Ti₅O₁₂材料具有诸多优点, 但是由于Li₄Ti₅O₁₂材料的电子结构中本征电导率很低, 影响其电化学性能, 限制了材料的应用^[7] ...

2007

2.39

0.0

... 55 V(vs Li⁺/Li), 能够避免生成锂枝晶, 安全性高并且价格低廉, 是很有潜力的动力型锂离子电池负极材料^[8,9,10,11] ...

2007

4.675

0.0

... 55 V(vs Li⁺/Li), 能够避免生成锂枝晶, 安全性高并且价格低廉, 是很有潜力的动力型锂离子电池负极材料^[8,9,10,11] ...

2006

4.675

0.0

... 55 V(vs Li⁺/Li), 能够避免生成锂枝晶, 安全性高并且价格低廉, 是很有潜力的动力型锂离子电池负极材料^[8,9,10,11] ...

2008

2.163

0.0

... 55 V(vs Li⁺/Li), 能够避免生成锂枝晶, 安全性高并且价格低廉, 是很有潜力的动力型锂离子电池负极材料^[8,9,10,11] ...

2007

3.777

0.0

Electrochimica Acta. 2007, 52(11):3704-3708 DOI:10.1016/j.electacta.2006.10.044

Improving the electrochemical performance of Li₄Ti₅O₁₂/Ag composite by an electroless deposition method

Abstract

Nano-sized silver particle (<20 nm) was highly dispersed on the surface of Li₄Ti₅O₁₂ particles by an electroless deposition method. The Ag additive played a positive role in improving the electrical contact between Li₄Ti₅O₁₂ particles and the current collector and therefore improved the high rate capacity of Li₄Ti₅O₁₂, but it did not take part in the electrochemical reactions with Li⁺ in Li₄Ti₅O₁₂/Ag composite during the cycling. The experimental results showed that the smaller the silver particles and the more homogeneous dispersion of silver particles in the Li₄Ti₅O₁₂ matrix, the better the cycling performance we obtained.

2006

2.046

0.0

2009

2.39

0.0

2011

1.527

0.0

... 05O₁₂样品, 晶胞体积变小, 说明Al进入尖晶石结构, 与文献的结果一致^[15] ...

2012

2.279

0.0

Journal of Solid State Electrochemistry. 2012, 16(1):205-211 DOI:10.1007/s10008-011-1305-z

Effect of Nb-doing on electrochemical stability of Li₄Ti₅O₁₂ discharged to 0 V

<li>1.School of Chemistry & Chemical Engineering, South China University of Technology, Wushan Road, Guangzhou, 510640, China</li>

Abstract
Li₄Ti_4.95Nb_0.05O₁₂ is synthesized by a citric acid-assistant sol–gel method. X-ray diffraction (XRD) reveals that highly crystalline Li₄Ti_4.95Nb_0.05O₁₂ without any impurity is obtained. The electrochemical performances of the Li₄Ti_4.95Nb_0.05O₁₂ and the Li₄Ti₅O₁₂ in the range from 0 to 2.5 V are investigated. The Li₄Ti_4.95Nb_0.05O₁₂ presents a higher specific capacity and better cycling stability than the Li₄Ti₅O₁₂ due to the improved conductivity. The Li₄Ti_4.95Nb_0.05O₁₂ exhibits a capacity as high as 231.2 mAh g⁻¹ after 100 cycles, which is much higher than the Li₄Ti₅O₁₂ (111.1 mAh g⁻¹). The effect of Nb-doping on electrochemical performance of Li₄Ti₅O₁₂ discharged to 0 V has also been discussed.

2012

2.279

0.0

Journal of Solid State Electrochemistry. 2012, 16(1):375-382 DOI:10.1007/s10008-011-1326-7

Synthesis and electrochemical performances of Li₄Ti_4.95Zr_0.05O₁₂/C as anode material for lithium-ion batteries

<li>1.Department of Chemistry, Harbin Institute of Technology, Harbin, 150001, China</li><li>2.College of Food Engineering of Harbin University of Commerce Chemistry Center, Harbin, 150076, China</li>

Abstract
Spinel Li₄Ti_5 − xZr_xO₁₂/C (x = 0, 0.05) were prepared by a solution method. The structure and morphology of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical performances including charge–discharge (0–2.5 V and 1–2.5 V), cyclic voltammetry, and ac impedance were also investigated. The results revealed that the Li₄Ti_4.95Zr_0.05O₁₂/C had a relatively smaller particle size and more regular morphology than that of Li₄Ti₅O₁₂/C. Zr⁴⁺ doping enhanced the ability of lithium-ion diffusion in the electrode. It delivered a discharge capacity 289.03 mAh g⁻¹ after 50 cycles for the Zr⁴⁺-doped Li₄Ti₅O₁₂/C while it decreased to 264.03 mAh g⁻¹ for the Li₄Ti₅O₁₂/C at the 0.2C discharge to 0 V. Zr⁴⁺ doping did not change the electrochemical process, instead enhanced the electronic conductivity and ionic conductivity. The reversible capacity and cycling performance were effectively improved especially when it was discharged to 0 V.

2011

1.987

0.0

2012

5.968

0.0

2005

0.0

0.568

... 聚丙烯酰胺(PAM)作为模板剂可以调控材料的形貌, 同时其在氮气气氛下产生的裂解碳可以改善材料的导电性能^[20], 然而, 采用PAM作为模板剂及碳源合成Li₄Ti_{4 ...}

2012

0.531

1.106

Journal of Inorganic Materials. 2012, 27(3):253-257 DOI:10.3724/SP.J.1077.2012.00253

Preparation and characterization of porous spherical Li₄Ti₅O₁₂/C anode material for lithium ion batteries

(Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China)

Titanium, lithium and carbon source compounds were mixed by ball milling firstly, then the slurry was spray dried to prepare spherical precursor. The porous spherical spinel Li₄Ti₅O₁₂/C powders were synthesized by calcining the precursor. XRD, SEM, TEM, BET testing and determination of the electrochemical properties show that the prepared Li₄Ti₅O₁₂/C powders are in form of spherical particles which is composed of nanocrystals. The specific surface area of Li₄Ti₅O₁₂/C powders is as high as 39.5 m²/g. The initial discharge specific capacities of the Li₄Ti₅O₁₂/C anode reach 172.2, 168.2 and 153.6 mAh/g at 0.1C, 1C and 5.0C rates, respectively. The Li₄Ti₅O₁₂/C anode also exhibits excellent cycle performance. The porous Li₄Ti₅O₁₂ material coated by carbon displays excellent high rate performance and cycling stability.

将钛源、锂源和碳源三种化合物一起球磨湿混成均匀浆料, 再依次经过喷雾干燥和高温煅烧制得晶粒表面包覆纳米碳层的多孔球形钛酸锂(Li₄Ti₅O₁₂)材料. 通过XRD、SEM、TEM、BET和电化学性能测试等分析手段表明, 合成出的Li₄Ti₅O₁₂/C材料为纳米一次粒子(晶粒)组成的球形二次粒子(颗粒), 具有较大的比表面积, 达到 39.5 m²/g; 在0.1C、1.0C和5.0C倍率下的首次放电比容量分别达到172.2、168.2和153.6 mAh/g, 并表现出优良的循环性能. 晶粒表面包覆碳的多孔Li₄Ti₅O₁₂材料具有明显的高倍率性能和循环稳定性优势.

... 在电极活性物质与电解液接触时, 材料比表面积的提高使得固液接触面积也得到提高, 这样可以缩短锂离子在固相中的扩散路程以及电子传输路径, 有利于降低活性材料在充放电过程中的极化程度, 因而有利于提高材料的倍率充放电性能^[21] ...

2009

2.39

0.0

... 图中高中频区的半圆反映的是电荷转移过程的阻抗以及电极和电解液间的界面容抗, 在低频区的直线反映的是锂离子在固体活性材料中扩散所引起的Warburg阻抗^[22,23,24] ...

2008

4.675

0.0

2011

0.0

1.09