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无机材料学报  2018 , 33 (5): 475-482 https://doi.org/10.15541/jim20170330

综述

锂离子电池负极材料钛酸锂的研究进展

谭毅1, 2, , 薛冰1, 2

大连理工大学1. 材料科学与工程学院
2. 辽宁省太阳能光伏系统重点实验室, 大连 116024

Research Progress on Lithium Titanate as Anode Material in Lithium-ion Battery

TAN Yi1, 2, , XUE Bing1, 2

1. School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China
2. Key Laboratoryfor Solar Energy Photovoltaic System of Liaoning Province, Dalian 116024, China

中图分类号:  TM912

文献标识码:  A

文章编号:  1000-324X(2018)05-0475-08

收稿日期: 2017-07-6

修回日期:  2017-08-22

网络出版日期:  2018-05-20

版权声明:   无机材料学报编委会 This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

作者简介:

作者简介: 谭 毅(1961-),男, 博士, 教授. E-mail: tanyi@dlut.edu.cn

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摘要

锂离子电池作为一种动力能源, 在电动汽车和各种储能系统中有着良好的应用前景。尖晶石结构的钛酸锂(Li4Ti5O12)负极材料具有较高的脱嵌锂电位平台、优异的循环稳定性、以及突出的安全性能, 被认为是一种非常有潜力的锂离子电池负极材料, 在锂离子动力电池中具有巨大的发展潜力。然而, 尖晶石型Li4Ti5O12存在着本征导电率低, 理论容量小等缺陷, 极大地限制了其规模化应用, 需要进一步改善和提高。本文总结了尖晶石型Li4Ti5O12材料在结构形貌、制备方法和性能方面的研究进展, 深入分析和讨论了离子掺杂、碳表面改性和纳米化等改性方法对尖晶石型Li4Ti5O12综合电化学性能的改善效果, 并展望了尖晶石型Li4Ti5O12作为锂离子电池负极材料未来的发展方向。

关键词： 钛酸锂 ; 负极材料 ; 锂离子电池

Abstract

With the increasing demand for light, small, high power rechargeable lithium ion batteries in the application of mobile phones, laptop computers, electric vehicles, hybrid electric vehicles, electrochemical energy storage, and smart grids, the development of anode materials with high safety, environmental benignity, high power density, and long cycle life is in progress in recent years. The spinel lithium titanium oxide (Li4Ti5O12) anode has become more attractive as alternative anode because of its high safety, abundant titanium dioxide raw materials, stable charge/discharge voltage plateau of 1.5 V (vs. Li/Li+), and excellent cycling performance due to its zero-strain volume during charge/discharge process. However, the commercial use of Li4Ti5O12 anode material has been hindered by the low intrinsic electronic conductivity. This review focuses on recent studies of the electronic structure and performance, synthesis methods and strategies for improvement in the lithium storage capacity, charge/discharge characteristics, then on its near future development.

Keywords： Li4Ti5O12 ; anode materials ; lithium-ion batteries

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谭毅, 薛冰. 锂离子电池负极材料钛酸锂的研究进展[J]. 无机材料学报, 2018, 33(5): 475-482 https://doi.org/10.15541/jim20170330

TAN Yi, XUE Bing. Research Progress on Lithium Titanate as Anode Material in Lithium-ion Battery[J]. Journal of Inorganic Materials, 2018, 33(5): 475-482 https://doi.org/10.15541/jim20170330

锂离子电池作为一种新型化学能源, 由于其具有循环寿命长、能量密度高、无记忆效应、环境友好等特点, 迅速发展成为最重要和最先进的二次电池[1,2]。锂离子电池已经被广泛开发应用在一些快速充电电子产品和电动汽车等领域[3,4]。目前, 碳材料是锂离子电池最常用的商业负极材料, 但由于金属锂与碳电极的电位接近, 快速充电或低温充电易发生“析锂”现象而引发安全隐患。另外碳负极在脱嵌锂离子的过程会发生体积形变, 导致不断有新的活性点产生, 从而使电池容量下降, 降低寿命。因此, 锂离子电池的发展迫切需要寻求安全可靠、寿命更长的新型负极来替代碳负极。其中钛酸锂就是这样一种很有潜力的负极材料。钛酸锂主要包括Li4TiO4、Li2TiO3、Li4Ti5O12和Li2Ti3O7。而Li4TiO4、Li2TiO3和Li2Ti3O7这三种锂钛氧化物受Ti化合价的影响很难合成纯相, 给制备工艺带来很大难度, 进而限制了这三种材料的应用; 尖晶石结构的Li4Ti5O12(LTO)凭借安全性高、优良的循环稳定性、平稳的充放电电压平台等优势, 在电化学领域倍受关注。

1 Li4Ti5O12的结构与性能

Li4Ti5O12是具有$\text{Fd\bar{3}m}$空间群和立方对称的尖晶石结构晶体[5]。Li4Ti5O12的嵌锂电位在1.55 V, 每个分子单元的Li4Ti5O12可以嵌入3个Li+, 对应的理论比容量为175 mAh/g。在Li4Ti5O12晶胞中, 3个Li占据8a位, Ti和剩余的1个Li 随机占据16d位, 可以写为Li(8a)[Li1/3Ti5/3](16d)O4(32e)。放电时, 要嵌入3个Li到尖晶石结构的16c位置, 原位于8a位置的3个Li由于静电排斥作用也转移到16c位置, 从Li4Ti5O12到Li7Ti5O12(可以写成Li2(16c)[Li1/3Ti5/3](16d)O4(32e))结构[6](如图1所示), 晶格常数由0.83595 nm变化到0.83538 nm, 对应晶胞体积变化仅0.2%[7,8,9]。因此可以说Li4Ti5O12是一种“零应变”材料, 具有优异的循环稳定性。另外, Li4Ti5O12有比较高的电位(1.55 V vs. Li/Li+, 碳0.1~0.2 V vs. Li/Li+), 不易析出枝晶, 避免了电池短路, 在充放电过程中安全性比较高[10]。

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图1   尖晶石型Li4Ti5O12与岩盐型Li7Ti5O12的结构[6]

Fig. 1   (a) Li4Ti5O12 spinel structure type and (b) Li7Ti5O12 rock salt structure type[6]

Li4Ti5O12的脱嵌锂(充放电)过程可以由核壳结构模型来描述[11,12]。如图2所示。当锂离子嵌入(放电)时, 尖晶石结构的Li4Ti5O12表面颗粒被还原并转化成岩盐结构的Li4Ti5O12。这个过程中形成的岩盐结构的壳随着锂离子嵌入深度的增加而变厚, 同时尖晶石结构的核心在逐渐缩小。放电结束后, 整个颗粒变成岩盐结构。相反, 充电过程中岩盐结构中的锂离子逐渐脱出进入尖晶石相, 完成脱锂过程。

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图2   Li4Ti5O12脱嵌锂过程示意图[12]

Fig. 2   Illustration of lithium insertion and extraction process of Li4Ti5O12 particle[12]

2 制备方法

制备Li4Ti5O12的方法主要有固相法、溶胶-凝胶法、水热法、喷雾热解法、熔盐法、微波法和静电纺丝法等。不同的制备方法对合成材料的形貌和性能影响非常大, 同一物料采用不同工艺制备, 会得到不同形貌结构、不同粒度、不同电化学性能的产品; 同时即使同一种制备工艺合成材料的性能又受锂源和钛源的配比、反应温度、反应时间、反应气体气氛环境等诸多因素的影响。

2.1 固相法

固相法是最传统的合成方法, 工艺简单, 是目前合成很多材料的首选方法。Li4Ti5O12材料通常以LiOH·H2O、Li2CO3、TiO2为原料, 通过高温(800~ 1000℃)、长时间(12 h以上)的煅烧形成。原料的配比[13]、反应温度[14]、反应时间[15]和混料方式[16,17]等合成条件都是直接影响产物Li4Ti5O12的结构、形貌和性能的重要因素。Han等[18]对高能球磨和普通球磨以及磨球的尺寸对合成Li4Ti5O12的影响进行了深入的研究。高能球磨能够为原料提供足够的机械活化能, 更有利于单一项的合成, 抑制金红石TiO2的形成, 并且能够缩短固相反应的扩散路径。当磨球尺寸为0.1 mm时, 制备的Li4Ti5O12粒径为175 nm, 拥有更为出色的电化学性能, 放电比容量为174 mAh/g。

2.2 溶胶-凝胶法

溶胶-凝胶法一般采用柠檬酸、草酸、丙稀酸等作为螯合剂, 以钛酸四丁酯作为钛源, 乙酸锂、氢氧化锂等作为锂源, 水、乙醇等作为分散系, 在酸的作用下发生氧化反应[19,20]。溶胶-凝胶法具有合成温度低, 时间短, 产物粒度小、分布窄、均一性好、比表面积大等优点[21]。Liu等[22]通过两相界面反应(环己烷/水)溶胶-凝胶法合成了粒径为100 nm的Li4Ti5O12负极材料, 该材料在10C和20C倍率下循环50次, 放电比容量分别保持在150 mAh/g和126.6 mAh/g。

2.3 水热法

水热法也是一种常见的湿法合成方法之一, 是将锂源和钛源置于高压釜中, 在一定温度和压力下, 在水、水溶液或蒸汽等流体中发生反应, 然后进一步煅烧结晶(500℃以上)。Zhu等[23]以廉价的H2TiO3做原料采用水热法制备了锯齿形纳米片组成的中空分层Li4Ti5O12。这种制备工艺的产量高达120 g/L, 并且拥有杰出的比容量, 在30C倍率下, 具有108 mAh/g的放电比容量, 循环1 000次后, 放电比容量仍可保持在94%。

2.4 其他方法

此外, 除了上述三种方法, 许多研究者还采用熔盐法[24]、静电纺丝法[25]、微波法[26,27]、喷雾热解法[28]等制备了性能优异的Li4Ti5O12材料。

3 Li4Ti5O12材料的改性

由于Ti原子3d电子层电子缺失, Li4Ti5O12的导电性很差, 其电子和离子导电率分别为10-13 S/cm和10-9~10-13 cm2/S, 这种绝缘属性严重影响了其在大电流充放电条件下的倍率性能。Li4Ti5O12充电过程主要分为三步, (1)电解液中的Li离子扩散; (2)Li4Ti5O12与电解液之间发生电荷转移; (3)Li离子嵌入固体Li4Ti5O12中。因此, 要提高Li4Ti5O12的倍率性能, 可以通过两种方法, 一是通过离子掺杂或表面改性的方法来提高离子扩散速率和电荷转移; 另一种方法是通过纳米化来缩短Li离子扩散的路径[8]。

3.1 离子掺杂

离子掺杂是提高Li4Ti5O12材料性能的有效方法之一。对Li4Ti5O12进行离子掺杂主要有两个目的, 一是降低其电极电位, 提高电池比容量; 二是提高其导电性, 降低电阻和极化。Li4Ti5O12的离子掺杂是指在Li+的8a位置或者Ti4+的16d位置引入高价阳离子, 或者在O2-的32e位置引入低价阴离子, 促使部分Ti4+转变为Ti3+, 以产生电荷补偿的混合物(Ti3+/Ti4+), 并增加电子浓度。同时, 掺杂会产生晶格扭曲, 在晶格中产生新的缺陷或空隙, 因此对离子传递的阻力发生变化, 锂离子扩散系数也随之改变。掺杂能够提高晶格电导率和锂离子扩散系数, 提高大倍率放电性能以及循环稳定性[29]。多种阴阳离子如Na+、Mg2+、Ca2+、Sc3+、Cr3+、Cu2+、Zn2+、Sr2+、Sn2+、La3+、Al3+、V5+、Zr4+、Ce4+、Gd3+、Ta5+、W6+、Sb5+、Nd3+、Ni2+、Mn4+、Fe3+、Zn2+、Nb5+、Ru4+、Bi3+、Mo6+、F-、Cl-、Br-等取代Li+、Ti4+、O2-各位点已被广泛研究, 并且系统的报道了离子价态和分布等结构性质和导电特性。表1总结了一些代表性阴阳离子掺杂改性Li4Ti5O12材料的性能。

表1   代表性阴阳离子掺杂Li4Ti5O12的Li, Ti, O各位点对性能的影响

Table 1   Summary of representative LTO doped with various cations/anions in the Li, Ti and O sites

IonRadius
/nm		Doping
content
molar ratio		Size/nmInitial discharge
capacity/(mAh.g-1)		Cycle performance/
(mAh.g-1)		MethodRef.
Cation doping in the Li sites(radius 0.076 nm)
Mg2+0.07200.20100-200190.0(1C)a179.0(1C, 100)b; 150.0(5C, 100)Solid state reaction[30]
Ca2+0.10000.101000-2000169.7(0.5C)162.4(1C, 100); 148.8(5C, 100)Solid state reaction[31]
Sc3+0.07450.05200174.0(1C); 94.0(40C)94.0(40C, 50)Sol-Gel[32]
Cu2+0.07300.05200-600158.0(0.1C)143.8(0.1C, 150)Sol-Gel[33]
La3+0.10320.0624.5169.0(0.1C)153.4(1C, 10); 146.9(5C, 10)Liquid method[34]
Cation doping in the Ti sites (radiusTi3+0.067 nm, Ti4+0.0605 nm)
Al3+0.05350.1550-200216.0(1C); 163.0(10C)180.0(5C, 50); 160.0(10C, 50)Cellulose-assisted glycine-nitratecombustion[35]
Zr4+0.07200.03200165.0(5C); 152.0(10C)142.0(5C, 200); 127.0(10C, 200)Liquid method[36]
Ce4+0.08700.10<1000190.0(0.2C); 40.0(2C)140.0(2C, 100)Solid state reaction[37]
Ta5+0.06400.05500-1000193.0(0.2C)132.0(5C, 100)Solid state reaction[38]
Anions doping in the O site (radius 0.14 nm)
Cl-0.1810.23-8 μm148.7(0.5C)133.8(0.5C, 50)Solid state reaction[39]
120.7(2C)
Br-0.1960.31-2 μm174.0(0.2C)138.0(10C, 100); 104.0(210C,100)Solid state reaction[40]

Note: a: “190.0(1C)” refers to the initial discharge capacity is 190.0 mAh.g-1 at 1C;b: “179.0(1C, 100)” indicates that discharge capacity is 179.0 mAh.g-1 after 100 cycles at 1C

新窗口打开

为了提高Li4Ti5O12的导电性, 有的研究者研究了两种元素(K+和Fe3+[41]、Mg2+和F-[42]、Na+和Zr4+[43]、Ni2+和Mn2+[44])共掺杂对Li4Ti5O12的影响。结果表明共掺杂能有效改善Li4Ti5O12的导电性, 使材料具有更好的倍率性能和循环稳定性。

另外, 有文献报道了尖晶石结构Li4Ti5O12在不同的电压范围下电化学性能不同, 特别是当延伸到0 V时, 有利于拓宽电化学反应窗口, 可以发挥优异的电化学性能。当放电电压延长到大约0 V时, 化合物中的所有Ti4+被氧化, Li4Ti5O12可以提供293~296 mAh/g的理论能量。嵌锂时, 锂离子可以嵌入Li4Ti5O12晶体的三个位置, 即(8a),(16c)和(48f), 表明Li+可以在低电位(<1.0 V vs. Li/Li+)嵌入Li4Ti5O12。这种低电位嵌锂过程将改善Li4Ti5O12的能量密度。放电过程中, 当电压范围在2.5~1.0 V时, 3个外加的Li+嵌入到Li4Ti5O12晶格的八面体(16c)位点, 同时, 最初位于四面体位点的Li+也迁移到八面体位置。当电压范围在1.0~0.01 V时, 另外2个Li+可插入岩盐结构Li4Ti5O12中仍然存在的间隙位置。空白的四面体(8a)位点可用于在1.0 V之下的锂离子嵌入, 从而在低电位下增强可逆容量。表2总结了低电位下一些代表性阳离子掺杂改性Li4Ti5O12材料的性能。

表2   低电位下代表性阳离子掺杂Li4Ti5O12的Li, Ti, O各位点对性能的影响

Table 2   Summary of representative LTO doped with various cations in the Li, Ti and O sites at low potential

IonRadius/nmDoping content
molar ratio		Size/
nm		Initial discharge
capacity/(mAh.g-1)		Cycle performance/
(mAh.g-1)		MethodRef.
Zn2+0.0740.201000-2000(0-2.5 V)216.4(0.5C, 30)Solid state
reaction		[6]
271.6(0.5C)a;
223.0(3C);		198.0(3C, 100)
186.0(5C, 200)
206.0(5C)
Nb5+0.0640.05(0-2.5 V)231.0(0.12C, 100)Sol-Gel[46]
351.0(0.12C)
Ru4+0.0620.05100-200(0.01-2.5 V)259.0(3C, 100);
131.0(60C, 100)		Reverse microemulsion
method		[47]
274.0(3C)
Bi+3+0.1030.10500-1000(0.01-2.5 V)203.0(1C, 50)Solid state
reaction		[48]
214.0(1C)

Note: a: “(0-2.5 V)271.6(0.5C)” refers to the initial discharge capacity is 271.6 mAh.g-1 at 0.5C from 0V to 2.5 V

新窗口打开

尖晶石型Li4Ti5O12由于八面体位置的空缺, 为Li+良导体。同时, 其中的Ti为最高的化合价+4价, 使其成为电子的不良导体。相反, 岩盐结构的Li4Ti5O12中的Ti平均价态为+3.4价, 是一种电子的良导体, 但随着电位降低, 嵌锂深度的增加, 由于其16c和8a位点均被Li+占据, 导致Li+的扩散路径受阻, Li+扩散系数的降低, 对电化学反应产生不利的影响。同时试验用的有机电解液在1.0~0.5 V之间有很强的还原性, 会在电极表面还原分解形成SEI膜[45], 引起电池内阻增加, 加剧电极极化, 缩短充放电平台。

3.2 碳材料改性

通过导电性高、结构多样的碳材料改善Li4Ti5O12材料的电化学性能是一种有效的方法。在Li4Ti5O12材料中添加不同形式的碳(如无定形碳、碳纳米管、石墨烯等), 能够促进相互连接的Li4Ti5O12颗粒之间的电子传输, 从而提高倍率性能、储锂能力和容量保持率。

3.2.1 表面碳包覆

碳包覆是目前最为常见的Li4Ti5O12改性方法, 碳包覆不仅可以改善表面电导率, 而且可以改善Li4Ti5O12材料和电解质之间的接触, 减小电池阻抗和电荷转移的阻力。加热使含碳物质分解, 在Li4Ti5O12表面形成厚度均匀的导电碳层, 增强了Li4Ti5O12的导电性, 从而改善其电化学性能。同时添加的碳源在煅烧过程中还能够抑制颗粒在高温热处理过程中的长大, 从而减小最终颗粒的粒径。碳含量高有助于提高表面电导率, 但也会产生较厚的碳包覆涂层, 这样会限制锂离子的扩散, 只有优化后均匀的碳包覆涂层可以提供良好的导电性和快速锂离子传输通道。表3总结了不同碳源、含量、厚度对碳包覆Li4Ti5O12性能的影响。

表3   不同碳源、含量、厚度对碳包覆Li4Ti5O12的性能影响

Table 3   The effects of the carbon source, carbon content, thickness, and graphitization on the electrochemical performance of the carbon coated Li4Ti5O12

Carbon sourceCarbon
content/wt%		Thickness/
nm		Initial discharge
capacity/(mAh.g-1)		Cycle performance/
(mAh.g-1)		MethodRef.
LPAN+CB3.643-5166.2(10C)141.9(10C, 200)Solid state reaction[49]
PEDOT10.0010168.7(1C)167.9(1C, 100)Hydrothermal reaction[50]
Sucrose8.602-4156.7(40C);
142.1(60C);
132.8(80C)		114.2(40C, 200);
98.1(60C, 200)
82.7(80C, 200)		One-step
liquid
process		[51]
Citric acid1.322-3165.7(1C);
161.7(5C);
153.9(10C);
147.9(20C)		144.9(20C, 50)Sol-Gel[52]
Glucose8.968170.9(0.5C)155.6(1C, 100)Hydrothermal-solid
state reaction		[53]

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3.2.2 石墨烯改性Li4Ti5O12复合材料

碳材料除可作为包覆层外, 还可利用自身的结构优势, 与Li4Ti5O12构成具有特殊形貌结构的复合材料。石墨烯是具有蜂窝结构的碳原子的二维大分子片, 具有很好的电子导电率和柔韧性, 是理想的导电添加剂[54]。Li等[55]将钛酸四丁酯和石墨烯分散在叔丁醇中, 通过微波照射加热到回流状态, 随后加入醋酸锂制备前驱体p- Li4Ti5O12/G。前驱体形态均匀, 尺寸超小, 通过煅烧形成Li4Ti5O12@G, Li4Ti5O12@G进一步与石墨烯片混合制备G@LI4TI5O12@G(图3)。所制备的G@Li4Ti5O12@G具有三维结构和分层多空分布。这种独特的结构提供了巨大的振实密度、快速电子转移和电解质运输的通道。该材料在5C倍率下的初始放电容量为168.6 mAh/g, 1 000次循环后容量仍然保持在163.8 mAh/g, 容量保持率达到97.2%。Yang等[56]使用冷冻干燥辅助微波照射的方法将包裹在碳壳内的Li4Ti5O12颗粒锚定到石墨烯纳米片(图4)。这种结构的设计通过连接石墨烯纳米片和碳层形成一个可以导电的三维网络, 有利于电子和锂离子的传递, 均匀的碳涂层和石墨烯纳米片的包覆, 改善了每个Li4Ti5O12颗粒的电子传导性。该材料在1C、2C、5C、10C和20C倍率下比容量分别为171.5、168.2、160.1、151.7和136.4 mAh/g。20C倍率20次循环后容量保持率仍为99.6%。Kim等[57]通过彻底清洗和透析制备了高质量、含最少杂质的石墨烯氧化物, 这使得每个单层石墨烯都能够成功的包裹每个Li4Ti5O12颗粒(图5)。单层石墨烯包覆Li4Ti5O12粒度200 nm, 表现出优异的性能, 即使在30C倍率下, 脱嵌锂比容量仍可达到130 mAh/g; 10C倍率下循环200次, 容量保持在151 mAh/g。

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图3   制备G@Li4Ti5O12@G过程示意图[55]

Fig. 3   The procedure for the preparation of G@LTO@G[55]

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图4   制备C-Li4Ti5O12/GNS过程示意图[56]

Fig. 4   Schematic illustration for the fabrication of C-LTO/GNS composite[56]

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图5   Li4Ti5O12表面石墨烯层数的电子传导和锂离子传输过程示意图[57]

Fig. 5   Schematic illustration representing the electron conduction Li+ and Li+ transport according to the number of graphene layers on the LTO surface[57]

3.3 形貌改进

Li4Ti5O12结构的纳米化, 或者制备出一维、二维或三维结构的Li4Ti5O12, 可以有效改善其电化学性能。纳米结构能够缩短电子和锂离子在Li4Ti5O12颗粒内的运输路径, 并且提供了更大的电极/电解液的接触面积, 有利于改善锂离子嵌入的动力学[58]。Luo等[59]通过水热法以葡萄糖作为碳源包覆锐钛矿TiO2, 在LiOH溶液中生成Li4Ti5O12/C纳米棒。与纯Li4Ti5O12相比, 这种纳米棒结构(图6)具有丰富的分层孔隙, 比表面积为107.8 m2/g, 增加了锂离子脱嵌的表面积, 加速了锂离子与电子的传递。在0.2C倍率下, 首次放电比容量为168.4 mAh/g, 库伦效率95%。Liu等[60]设计了一种具有高导电性的自支撑Li4Ti5O12-C纳米管阵列结构(图7)。Li4Ti5O12纳米管阵列通过简单的基于模板溶液法直接生长在不锈钢箔上, 再在其内外表面均匀涂覆碳层, 进一步提高了导电性。该材料在30C、60C、100C倍率下, 可逆比容量分别为135, 105和80 mAh/g。并且在10C倍率下循环500次后, 容量保持为144 mAh/g。

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图6   Li4Ti5O12的TEM照片(a), Li4Ti5O12/C纳米棒的TEM照片(b, c)和HRTEM照片(d)[59]

Fig. 6   (a) TEM image of the Li4Ti5O12 nanoparticles and (b, c) TEM and (d) HRTEM images of Li4Ti5O12/C nanorods[59]

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图7   不同放大倍数的Li4Ti5O12-C纳米管阵列的SEM照片[60]

Fig. 7   Different magnification SEM images of Li4Ti5O12-C nanotube arrays on stainless steel foil[60]

4 展望

尖晶石结构的Li4Ti5O12具有安全性高、结构稳定、循环性能好, 1.5 V(vs. Li/Li+)稳定的电压平台等优点, 在动力储能方面备受瞩目, 成为最有潜力的下一代锂电池负极材料之一。当前对Li4Ti5O12材料的研究仍存在不足, 需要从以下几个方面解决：

1)锂离子电池负极材料的研究重点是高比容量、高效率、循环稳定和耐高低温环境。Li4Ti5O12作为锂离子电池负极材料, 在循环稳定性和安全性方面优势明显, 但仍无法满足锂离子蓄电池对负极材料容量的要求(碳材料372 mAh/g)。因此需要通过优化结构等方法深入研究Li4Ti5O12不同形貌与尺寸对于性能的影响, 进一步提高其能量密度。

2)针对Li4Ti5O12导电率低的缺陷, 通过离子掺杂能够改善Li4Ti5O12材料的导电性, 已有很多研究, 但对于哪种掺杂离子对Li4Ti5O12材料的改性最大, 其掺杂的位置、机理等有待更深入研究。尤其是共掺杂方法, 对Li4Ti5O12材料结构变化、界面特征、共掺杂离子与基体之间的相互作用以及离子分布仍需要进一步研究。

3)目前对Li4Ti5O12材料高低温环境性能研究的比较少, 今后的研究工作重点应放在高低温环境对Li4Ti5O12电性能的影响, 加快促进Li4Ti5O12材料在工业上的应用。

参考文献

[1] LI Z Y, DING F X, ZHAO Y G,et al.

Synthesis and electrochemical performance of Li4Ti5O12 submicrospheres coated with TiN as anode materials for lithium-ion battery

. Ceram. Int., 2016, 42(14): 15464-15470.

[本文引用: 1]     

[2] HUI Y N, CAO L Y, XU Z W,et al.

In situ synthesis of core-shell Li4Ti5O12@polyaniline composites with enhanced rate performance for lithium-ion battery anodes

. J. Mater. Sci. Techno., 2016, 33(3): 231-238.

[本文引用: 1]     

[3] CHEN S, XIN Y L, ZHOU Y Y,et al.

Self-supported Li4Ti5O12 nanosheet arrays for lithium ion batteries with excellent rate capability and ultralong cycle life

. Energy Environ. Sci., 2014, 7(6): 1924-1930.

[本文引用: 1]     

[4] YI T F, YANG S Y, XIE Y.

Recent advances of Li4Ti5O12 as a promising next generation anode material for high power lithium- ion batteries

.J. Mater. Chem. A, 2015, 3(11): 5750-5777.

[本文引用: 1]     

[5] BORGHOLS W J H, WAGEMAKER M, LAFONT U,et al.

Size effects in the Li4+xTi5O12 spinel

. J. Am. Chem. Soc., 2009, 131(49): 17786-17792.

[本文引用: 1]     

[6] YI T F, LIU H P, ZHU Y R,et al.

Improving the high rate performance of Li4Ti5O12 through divalent zinc substitution

. J. Power Sources, 2012, 215: 258-265.

[本文引用: 3]     

[7] WIKENING M, IWANIAK W, HEINE J,et al.

Microscopic Li self-diffusion parameters in the lithiated anode material Li4+xTi5O12(0 < or = x < or = 3) measured by 7Li solid state NMR. Phys

. Chem. Chem. Phys., 2007, 9(47): 6199-6202.

[本文引用: 1]     

[8] YANG S, WANG Q F, LU M W, et al.

Synthesis of graphitized carbon, nanodiamond and graphene supported Li4Ti5O12 and comparison of their electrochemical performance as anodes for lithium ion batteries

. Appl. Surf. Sci., 2016, 389: 428-437.

[本文引用: 2]     

[9] ZHU G N, WANG Y G, XIA Y Y.

Ti-based compounds as anode materials for Li-ion batteries

.Energy Environ. Sci., 2012, 5(5): 6652-6667.

[本文引用: 1]     

[10] Yang L Y, LI H Z, LIU J,et al.

Effects of TiO2 phase on the performance of Li4Ti5O12 anode for lithium-ion batteries

. J. Alloys Compd., 2016, 689: 812-819.

[本文引用: 1]     

[11] MA J, WANG C, WROBLEWSKI S.

Kinetic characteristics of mixed conductive electrodes for lithium ion batteries

.J. Power Sources, 2007, 164(2): 849-856.

[本文引用: 1]     

[12] TAKAMI N, HOSHINA K, INAGAKI H.

Lithium diffusion in Li4/3Ti5/3O4 particles during insertion and extraction

.J. Electrochem. Soc., 2011, 158(6): A725-A730.

[本文引用: 3]     

[13] LIU W, ZHANG J, WANG Q,et al.

The effects of Li2CO3 particle size on the properties of lithium titanate as anode material for lithium-ion batteries

. Ionics, 2014, 20(11): 1553-1560.

[本文引用: 1]     

[14] CHEN C, SPEARS M, WONDRE F, et al.

Crystal growth and superconductivity of LiTi2O4 and Li1+1/3Ti2-1/3O4

.J. Cryst. Growth, 2003, 250(1/2): 139-145.

[本文引用: 1]     

[15] GUERFI A, SEVIGNY S, LAGACE M,et al.

Nano-particle Li4Ti5O12 spinel as electrode for electrochemical generators

. J. Power Sources, 2003, 119(121): 88-94.

[本文引用: 1]     

[16] MICHALSKA M, KRAJEWSKI M, ZIOLKOWSKA D,et al.

Influence of milling time in solid-state synthesis on structure, morphology and electrochemical properties of Li4Ti5O12 of spinel structure

. Powder Technol., 2014, 266(6): 372-377.

[本文引用: 1]     

[17] SENNA M, FAVIAN M, KAVAN L,et al.

Electrochemical properties of spinel Li4Ti5O12 nanoparticles prepared via a low-temperature solid route

. J. Solid State Electrochem., 2016, 20(10): 2673-2683.

[本文引用: 1]     

[18] HAN S W, JEONG J, YOON D H.

Effects of high-energy milling on the solid-state synthesis of pure nano-sized Li4Ti5O12 for high power lithium battery applications

.Appl. Phys. A, 2014, 114(3): 925-930.

[本文引用: 1]     

[19] WANG Y Q, ZHAO J, QU J,et al.

Investigation into the surface chemistry of Li4Ti5O12 nanoparticles for lithium ion batteries

. Appl. Mater. Interfaces, 2016, 8(39): 26008-26012.

[本文引用: 1]     

[20] QIU C X, YUAN Z Z, LIU L,et al.

Sol-Gel preparation and electrochemical properties of La-doped Li4Ti5O12 anode material for lithium-ion battery

. J. Solid State Electrochem., 2013, 17(3): 841-847.

[本文引用: 1]     

[21] MOHAMMADI M R, FRAY D J.

Low temperature nanostructured lithium titanates: controlling the phase composition, crystal structure and surface area

.J. Sol-Gel Sci. Techn., 2010, 55(1): 19-35.

[本文引用: 1]     

[22] LIU G Y, ZHANG R X, BAO K Y,et al.

Synthesis of nano- Li4Ti5O12 anode material for lithium ion batteries by a biphasic interfacial reaction route

. Ceram. Int., 2016, 42(9): 11468-11472.

[本文引用: 1]     

[23] ZHU K X, GAO H Y, HU G X,et al.

Scalable synthesis of hierarchical hollow Li4Ti5O12 microspheres assembled by zigzag-like nanosheets for high rate lithium-ion batteries

. J. Power Sources, 2017, 340: 263-272.

[本文引用: 1]     

[24] GUO Q J, LI S Y, WANG H,et al.

Molten salt synthesis of nano-sized Li4Ti5O12 doped with Fe2O3 for use as anode material in the lithium ion battery

. RSC Adv., 2014. 4(104): 60327-60333.

[本文引用: 1]     

[25] ZHAO Y G, LI J L, LI Z Y,et al.

Pr-modified Li4Ti5O12 nanofibers as an anode material for lithium-ion batteries with outstanding cycling performance and rate performance

. Ionics, 2017. 23(3): 597-605.

[本文引用: 1]     

[26] YANG L H, DONG C D, GUO J.

Hybrid microwave synthesis and characterization of the compounds in the Li-Ti-O system

.J. Power Sources, 2008, 175(1): 575-580.

[本文引用: 1]     

[27] LI J, JIN Y L, ZHANG X G,et al.

Microwave solid-state synthesis of spinel Li4Ti5O12 nanocrystallites as anode material for lithium- ion batteries

. Solid State Ionics, 2007, 178(29/30): 1590-1594.

[本文引用: 1]     

[28] JIA X L, KAN Y F, ZHU X,et al.

Building flexible Li4Ti5O12/CNT lithium-ion battery anodes with superior rate performance and ultralong cycling stability

. Nano Energy, 2014, 10: 344-352.

[本文引用: 1]     

[29] WOLFENSTINE J, ALLEN J L.

Electrical conductivity and charge compensation in Ta doped Li4Ti5O12

.J. Power Sources, 2008, 180(1): 582-585.

[本文引用: 1]     

[30] LI F Y, ZHENG M, LI J,et al.

Preparation and electrochemical performance of Mg-doped Li4Ti5O12 nanoparticles as anode materials for lithium-ion batteries

. Int. J. Electrochem. Sci., 2015, 10(12): 10445-10453.

[31] ZHANG Q Y, ZHANG C L, LI B,et al.

Preparation and electrochemical properties of Ca-doped Li4Ti5O12 as anode materials in lithium-ion battery materials for flexible Li-ion batteries

. Electrochim. Acta, 2013, 98(16): 146-152.

[32] ZHANG Y Y, ZHANG C M, LIN Y,et al.

Influence of Sc3+ doping in B-site on electrochemical performance of Li4Ti5O12 anode materials for lithium-ion battery

. J. Power Sources, 2014, 250(3): 50-57.

[33] GE Y Q, JIANG H, FU K,et al.

Copper-doped Li4Ti5O12/carbon nanofiber composites as anode for high-performance sodium-ion batteries

. J. Power Sources, 2014, 272: 860-865.

[34] BAI Y J, GONG C, QI Y X,et al.

Excellent long-term cycling stability of La-doped Li4Ti5O12 anode material at high current rates

. J. Mater. Chem., 2012, 22(36): 19054-19060.

[35] 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

. J. Mater. Chem., 2012, 22(16): 8013-8021.

[36] CHEN Y J, MU D B, HANG R,et al.

The Improvement of Discharge Capacity of Zr-doped Lithium Titanate for Lithium Ion Batteries

. Matec Web Conf., 2016, 67: 06028.

[37] ZHOU T P, FENG X Y, GUO X,et al.

Solid-state synthesis and electrochemical performance of Ce-doped Li4Ti5O12 anode materials for lithium-ion batteries

. Electrochim. Acta, 2015, 174: 369-375.

[38] GUO M, WANG S Q, DING L X,et al.

Tantalum-doped lithium titanate with enhanced performance for lithium-ion batteries

. J. Power Sources, 2015, 283(25): 372-380.

[39] HUANG Y D, QI Y L, JIA D Z,et al.

Synthesis and electrochemical properties of spinel Li4Ti5O12-xClx anode materials for lithium- ion batteries

. J. Solid State Electrochem., 2012, 16(5): 2011-2016.

[40] WANG J Q, YANG Z Z, LI W H,et al.

Nitridation Br-doped Li4Ti5O12 anode for high rate lithium ion batteries

. J. Power Sources, 2014, 266(1): 323-331.

[41] DING K Q, ZHAO J, SUN Y Z,et al.

Using potassium ferricyanide as a dopant to prepare K and Fe co-doped Li4Ti5O12

. Ceram. Int., 2016, 42(16): 19187-19194.

[本文引用: 1]     

[42] BAI X, LI W, WEI A J,et al.

Preparation and electrochemical properties of Mg2+ and F- co-doped Li4Ti5O12 anode material for use in the lithium-ion batteries materials for flexible Li-ion batteries

. Electrochim. Acta, 2016, 222: 1045-1055.

[本文引用: 1]     

[43] XU P, HUANG X B, REN Y R,et al.

Na+ and Zr4+ co-doped Li4Ti5O12 as anode materials with superior electrochemical performance for lithium ion batteries

. RSC Adv., 2016, 6(93): 90455-90461.

[本文引用: 1]     

[44] LONG W M, WANG X Y, YANG S Y,et al.

Electrochemical properties of Li4Ti5-2xNixMnxO12 compounds synthesized by Sol-Gel process

. Mater. Chem. Phys., 2011, 131(1): 431-435.

[本文引用: 1]     

[45] SHKROB I A, ZHU Y, MARIN T W,et al.

Reduction of carbonate electrolytes and the formation of solid-electrolyte interface (SEI) in lithium-ion batteries. 1. spectroscopic observations of radical intermediates generated in one-electron reduction of carbonates

. J. Phys. Chem. C, 2013, 117(38): 19255-19269.

[本文引用: 1]     

[46] TIAN B B, XIANG H F, ZHANG L,et al.

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

. J. Solid State Electrochem., 2012, 16(1): 205-211.

[47] WANG W, WANG H L, WANG S B,et al.

Ru-doped Li4Ti5O12 anode materials for high rate lithium-ion batteries

. J. Power Sources, 2013, 228(11): 244-249.

[48] SUBBURAJ T, PRASANNA K, KIM K J,et al.

Structural and electrochemical evaluation of bismuth doped lithium titanium oxides for lithium ion batteries

. J. Power Sources, 2015, 280: 23-29.

[49] HUANG P X, TANG S H, PENG H,et al.

In-situ synthesis of graphitized-carbon coated Li4Ti5O12/C anode for high-rate lithium ion batteries

. Mater. Sci. Forum, 2015, 814: 358-364.

[50] WANG X Y, SHEN L F, LI H S,et al.

PEDOT coated Li4Ti5O12 nanorods: soft chemistry approach synthesis and their lithium storage properties

. Electrochim. Acta, 2014, 129(16): 283-289.

[51] MU D B, CHEN Y J, WU B R,et al.

Nano-sized Li4Ti5O12/C anode material with ultrafast charge/discharge capability for lithium ion batteries

. J. Alloys Compd., 2016, 671: 157-163.

[52] KUO Y C, LIN J Y.

One-pot Sol-Gel synthesis of Li4Ti5O12/C anode materials for high-performance Li-ion batteries

.Electrochim. Acta, 2014, 142: 43-50.

[53] GAO L, LIU R J, HU H,et al.

Carbon-decorated Li4Ti5O12/rutile TiO2 mesoporous microspheres with nanostructures as high-performance anode materials in lithium-ion batteries

. Nanotechnology, 2014, 25(17): 175402-175410.

[54] XUE R, YAN J W, JIANG L,et al.

Fabrication of lithium titanate/ graphene composites with high rate capability as electrode materials for hybrid electrochemical super capacitors

. Mater. Chem. Phys., 2015, 160: 375-382.

[本文引用: 1]     

[55] LI R Y, CHEN T Y, SUN B B,et al.

Novel lithium titanate-graphene hybrid containing two graphene conductive frameworks for lithium- ion battery with excellent electrochemical performance

. Mater. Res. Bull., 2015, 70: 965-975.

[本文引用: 3]     

[56] YANG X J, ZHENG A B, WANG X L,et al.

Graphene nanosheet and carbon layer co-decorated Li4Ti5O12 as high performance anode material for rechargeable lithium-ion batteries

. Ceram. Int., 2017, 43(3): 3252-3258.

[本文引用: 3]     

[57] KIM J, LEE K E, KIM K H,et al.

Single-layer graphene-wrapped Li4Ti5O12 anode with superior lithium storage capability

. Carbon, 2017, 114: 275-283.

[本文引用: 3]     

[58] KIM K T, YU C Y, YOON C S,et al.

Carbon-coated Li4Ti5O12 nanowires showing high rate capability as an anode material for rechargeable sodium batteries

. Nano Energy, 2015, 12: 725-734.

[本文引用: 1]     

[59] LUO H J, SHEN L F, RUI K,et al.

Carbon coated Li4Ti5O12 nanorods as superior anode material for high rate lithium ion batteries

. J. Alloys Compd., 2013, 572: 37-42.

[本文引用: 1]     

[60] LIU J, SONG K, AKEN P A,et al.

Self-supported Li4Ti5O12-C nanotube arrays as high-rate and long-life anode materials for flexible Li-ion batteries

. Nano Lett., 2014, 14(5): 2597-2603.

[本文引用: 1]     

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