相对较高Cl掺杂对Li4Ti5O12负极材料的电化学性能的影响
Effect of Relatively High Cl-Doping on Electrochemical Properties of Li4Ti5O12 Anode Materials
DOI: 10.12677/AAC.2023.131008, PDF, HTML, XML, 下载: 183  浏览: 245  国家自然科学基金支持
作者: 吴逸秋, 王 影*, 张文龙, 汪鹏程, 董 浩, 和保佳:上海工程技术大学机械与汽车工程学院,上海
关键词: Cl掺杂负极材料锂离子电池Li4Ti5O12Li2O/CuOCl-Doping Anode Materials Lithium-Ion Battery Li4Ti5O12 Li2O/CuO
摘要: 本研究通过固相法合成了少量Cl掺杂样品(Cl-LTO-1:80,1:80为LiCl与LTO质量比)和相对较高Cl掺杂样品(Cl-LTO-1:16)。X射线衍射(XRD)表明,掺杂Cl不会改变立方尖晶石钛酸锂的结构,并检测到Li2O的存在。使用循环伏安法(CV)、电化学阻抗谱(EIS)、倍率测试和充放电循环性能测试来表征其电化学性能。结果表明,所有掺杂样品的放电容量都有所提高。在所有样品中,Cl-LTO-1:16样品的放电容量在不同倍率下(0.2 C, 0.5 C, 1 C, 2 C)最高。在0.2 C倍率下,Cl-LTO-1:16样品的放电容量比原始Li4Ti5O12样品高出64%。高掺杂样品的显著改善可归因于Cl-LTO-1:16样品中铜箔和LTO电极材料之间的Li2O/CuO中间层,该中间层由铜箔表面自组装的少量CuO和固相法制备过程中产生的Li2O组成。
Abstract: In this study, a weakly doped sample (Cl-LTO-1:80, 1:80 is the mass ratio of LiCl to LTO) and a relatively high doped sample (Cl-LTO-1:16) have been synthesized by the solid-state method. X-Ray Diffraction (XRD) exhibited that Cl-doping did not change the structure of cubic spinel LTO and the existence of Li2O was detected. Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), rate capability and charge/discharge cycling performance tests were used to characterize their electrochemical properties. The results showed the discharge capacity was improved for all the doped samples. The discharge capacity of the Cl-LTO-1:16 is the highest among all samples at a different rate (0.2 C, 0.5 C, 1 C, 2 C). At the rate of 0.2 C, the discharge capacity of the Cl-LTO-1:16 is elevated to an impressive level of 64% higher than that of pristine Li4Ti5O12 anode. The significant improvement of high doped sample can be attributed to a Li2O/CuO intermediate layer between the copper foil and LTO electrode material in Cl-LTO-1:16, which is composed of a small amount of CuO self-assembled on the surface of copper foil and Li2O prepared by the solid-state method.
文章引用:吴逸秋, 王影, 张文龙, 汪鹏程, 董浩, 和保佳. 相对较高Cl掺杂对Li4Ti5O12负极材料的电化学性能的影响[J]. 分析化学进展, 2023, 13(1): 76-84. https://doi.org/10.12677/AAC.2023.131008

1. 引言

尖晶石Li4Ti5O12 (LTO) [1] 是一种很有前景的锂电池负极材料。作为一种“零应变”插入材料,LTO在Li+嵌入/脱出过程中只有0.3%的体积变化。此外,LTO的充放电平台(1.55 V,对Li+/Li电位)高于电解质溶剂的还原电位,这不仅阻止了固体电解质界面(SEI)的形成,而且也使得难以形成锂枝晶 [2] [3] 。这不仅改善了电化学性能,还使得电池的应用更加安全。然而,钛酸锂负极材料的理论比容量低、导电性差,限制了其在工业上的应用 [4] 。为此,研究人员提供了许多解决方案,如金属阳离子掺杂(Ca2+ [5] [6] 、Zr4+ [7] 、Al3+ [8] 、La3+ [9] 等)、非金属阴离子掺杂(F [10] [11] 、N [12] 、Br [13] 等)、共掺杂(Mg/La [14] 、Mg/Zr [15] 、Na/Nb [16] 等)、表面涂层(Carbon [17] 、TiN [18] 、AlF3 [19] 、Li3PO3 [20] 、ZnO [21] 等)和各种复合材料的开发(RGO [22] 、Ag [23] 、CNT [24] 、金属氧化物 [25] 等)。

离子掺杂策略是提高LTO导电性的有效方法,关于在锂或钛位置掺杂金属离子的报道很多。与金属阳离子掺杂相比,在氧位掺杂非金属阴离子(尤其是Cl掺杂)的报道较少。2012年,Huang等人 [26] 制备了Li4Ti5O12−xClx (x = 0.1、0.2和0.3),将Cl掺杂到LTO中。其中,Li4Ti5O11.8Cl0.2样品在0.5 C倍率下的放电容量为148.7 mAh g−1,比原始Li4Ti5O12 (129.8 mAh g−1)的放电容量高出了14.56%。在2020年,Salvatore和他的同事 [27] 报告称,在氧位掺杂Cl有效地提高了锂离子/电子电导率,并将循环容量提高了12%,他们探索了为什么掺杂Cl会提高Cl-LTO电极的性能。其原因如下:1) 与O2−相比,Cl具有更大的粒径,可以拓宽离子通道,从而提高离子电导率。2) Cl替代Li4Ti5O12中的O2−。作为电荷损失的补偿,Ti4+被还原为Ti3+,这增加了轨道中电子的浓度,从而提高了电子电导率。

目前,关于氯掺杂钛酸锂的报道很少,而且在现有的研究 [26] [27] 中,Cl掺杂量仍然保持在一个较小的范围内,容量提升也很有限。在本研究中,通过增加Cl的掺杂量来探索掺杂了相对大量Cl的LTO电极的电化学性能,通过固相法制备了在LTO中掺杂少量Cl的样品(Cl-LTO-1:80,1:80是LiCl和LTO的质量比)和在LTO中掺杂相对大量Cl的样品(Cl-LTO-1:16,1:16是LiCl和LTO质量比)。对于Cl-LTO-1:16样品,在固态法制备Cl-LTO粉末的过程中,生成了Li2O,在随后的电极制备过程中,少量CuO原位自组装在铜箔表面,然后在LTO电极材料和铜箔之间形成Li2O/CuO中间层。通过与Cl-LTO-1:80样品的比较,讨论了Li2O/CuO中间层对容量提高的影响,对Cl-LTO-1:16样品的结构、形貌和电化学性能也进行了研究。

2. 实验

2.1. Cl-LTO-1:80和Cl-LTO-1:16样品的制备

首先,将LiCl (99%,Adamas-beta,中国)和LTO粉末(PLB-H5,天城河,中国)在重量比为1:16和1:80的研钵中研磨1小时,以制备两种前驱体粉末(Cl-LTO-1:80和Cl-LTO-1:16)。其次,将前驱体粉末在610℃ (氯化锂熔点)下均匀加热1小时,并在充满流通氩气的管式炉中于700℃加热3小时,然后在氩气保护下自然冷却至室温。然后,将合成样品与PVDF (AR,SCRC,中国)和Super P (40 nm,TIMCAL,瑞士)按8:1:1的质量比倒入N-甲基吡咯烷酮溶剂中,并在磁力搅拌器中以800 rpm搅拌6小时,将搅拌均匀分散的浆料用涂布试验机涂覆到铜箔上,涂覆厚度为200 μm。接下来,在100℃的电热干燥箱中干燥电极2小时,直到电极表面没有明显的流动性溶液。然后,将电极放在110℃的真空烘箱中干燥24小时。最后,先用直径15.6 mm圆形冲子对完全干燥的电极进行切片,再对电极片进行称重和测试。

2.2. 结构和形貌表征

用型号为S-4800的冷场发射扫描电镜(Hitachi,日本)观察电极的形貌。采用使用X Perp PRO型X射线衍射仪对电极样品的相组成和晶体结构进行了表征,Cu-Kα,样本扫描范围为10˚到90˚,扫描速率0.03 min−1

2.3. 电化学测试

本实验采用扣式电池测量了氯掺杂钛酸锂复合电极的电化学性能。正极采用Cl-LTO电极和原始LTO电极,负极采用锂箔。使用聚丙烯薄膜(Celgard 2400)作为隔膜。扣式电池在充满氩气的手套箱中组装。在LAND电池测试系统中,以0.2 C、0.5 C、1 C、2 C和1 C的倍率在1至3 V之间进行充电/放电测试。在LAND电池测试系统中,以0.1C的速率在1至3 V之间进行10次循环的充放电循环性能,再以1 C的速率进行90次循环。在电化学工作站(CHI660E,上海晨华,中国)上,以0.1 mV/s的扫描速度进行循环伏安(CV),电压范围为1.0 V~3.0 V。电化学阻抗谱(EIS)测试也在电化学工作站上进行,交流扰动信号的振幅为10 mV,频率范围为0.01~105 Hz。

3. 结果与讨论

3.1. 结构和形貌分析

图1(a)为原始LTO,Cl-LTO-1:80和Cl-LTO-1:16样品的XRD图。其中,在18.4˚、35.6˚、37.1˚、43.3˚、47.4˚、57.2˚、62.8˚、66.1˚、74.3˚、75.4˚和79.4˚处的衍射峰对应于具有FD-3m空间群的Li4Ti5O12的立方尖晶石结构。43.3˚、50.4˚和74.1˚处的衍射峰对应于铜箔的(111)、(200)和(220)晶面。32.9˚处的衍射峰不明显。根据相关文献 [28] ,它对应于Li2O的晶面(111)。推测LiCl分解为Li+和Cl,其中Cl取代了Li4Ti5O12中的部分O2−,被取代的部分O2−于LiCl分解出的Li+结合产生Li2O。掺杂Cl的样品与原始LTO样品的XRD谱图基本一致,这证明掺杂Cl不会改变立方尖晶石钛酸锂的结构。从图1(b)可以看出,与原始LTO样品相比,Cl-LTO-1:80和Cl-LTO-1:16样品中对应钛酸锂的衍射峰略有左移,并且随着掺杂量的增加,偏移量增加,这表明Cl成功掺杂进了钛酸锂内并且对钛酸锂晶格参数产生影响。XRD拟合结果也可以证明这一点。结果表明,随着掺杂量的增加,晶格参数从Pristine LTO的8.3222增加到Cl-LTO-1:80的8.3297,再增加到Cl/LTO-1:16的8.532。这是因为Cl (167 pm)的半径大于O2− (140 pm)。一般来说,掺杂Cl可能会影响LTO的内部晶体结构,但不会改变LTO的结构。图2中的SEM图像也证实了这一点。与原始LTO相比,Cl掺杂样品的形貌仍然是立方尖晶石结构,并且粒径几乎没有变化(约3 μm~10 μm)。但粒子有一定程度的团聚,粒子钝化轻微,一些小的Li2O粒子均匀分布在粒子表面。

Figure 1. (a) XRD patterns of pristine LTO, Cl-LTO-1:80 and Cl-LTO-1:16; (b) Magnified pattern of Li4Ti5O12 (111) crystal plane

图1. (a)原始钛酸锂、Cl-LTO-1:80和Cl-LTO-1:16样品的XRD图;(b) Li4Ti5O12 (111)晶面处放大图

Figure 2. SEM images of the pristine LTO sample (a) (c) and Cl-LTO-1:16 sample (b) (d)

图2. 原始钛酸锂样品(a) (c)和Cl-LTO-1:16 (b) (d)样品的SEM图

3.2. 充放电循环性能和倍率性能分析

图3(a)显示了原始LTO、Cl-LTO-1:80和Cl-LTO-1:16样品的充放电循环性能,所有样品均在1到3 V之间以0.2 C的倍率进行10个循环,再以1 C的倍率完成90个循环。从图3(b)可以看出,Cl掺杂样品的放电容量高于原始LTO在0.2 C和1 C倍率下的放电容量,其中Cl-LTO-1:16样品的放电容量最高。在0.2 C的速率下(第三周循环时),Cl-LTO-1:80样品的放电容量为192.3 mAh g−1,比原始LTO样品(156.8 mAh g−1)的放电容量高22.6%。Cl-LTO-1:16样品的放电容量为257 mAh g−1,比Cl-LTO-1:80样品高33.6%,比原始LTO样品高64%。在1 C的倍率下(第15周循环时),Cl-LTO-1:80样品的放电容量降至157 mAh g−1,比原始LTO样品(140.1 mAh g−1)的放电容量高12.1%。Cl-LTO-1:16样品的放电容量为213.3 mAh g−1,比Cl-LTO-1:80样品高35.9%,比原始LTO样品的放电容量高52.2%。Cl-LTO-1:80样品的改善效果与此前关于Cl掺杂LTO的报告相似 [26] [27] 。因此,与原始LTO样品相比,Cl-LTO-1:80样品的放电容量增加的原因可归因于Cl掺杂。Cl取代了O2−,这不仅拓宽了离子通道,而且使Ti4+还原为Ti3+,从而提高了电子/离子电导率。这些因素使更多的氧化还原活性电位能够通过电化学方式获得,从而提高放电容量。然而,Cl-LTO-1:16样品放电容量增加更多,这不仅是因为Cl取代了O2−,还归因于铜箔和钛酸锂活性材料之间生成的Li2O/CuO中间层,这一中间层由铜箔表面自组装的CuO和固相法制备过程中产生的Li2O组成,这一中间层提供了一定的容量。推测CuO的生成方法如下:(1) 搅拌过程中,水蒸气进入电极浆液。(2) 将浆液涂敷在铜箔上,铜与浆液中的水还有空气中的氧气、二氧化碳反应生成碱式碳酸铜。随后在恒温干燥箱中,电极处于高温干燥过程中,碱式碳酸铜高温分解为CuO。化学反应方程式如下:

2Cu+H 2 O+O 2 + CO 2 Cu 2 ( OH ) 2 CO 3 (1)

Cu 2 ( OH ) 2 CO 3 Δ 2CuO+H 2 O+CO 2 (2)

图3(b)和图3(c)显示了原始LTO样品、Cl-LTO-1:80样品和Cl-LTO-1:16样品在第三周和第十五周的充放电曲线。从中我们可以观察到,除了电压1.55 V处钛酸锂的充放电平台外,还有几个充放电平台。在1 V~3 V充电期间,充电曲线根据不同的斜率分为两个电压范围,分别为1.6 V~2.2 V和2.2 V~3 V,对应于Cu氧化为Cu2O和Cu2O氧化为CuO。在3 V~1 V放电期间,放电曲线根据不同的斜率分为三个电压范围,分别为2.3 V~1.7 V、1.7 V~1.55 V、1.45 V~1 V。根据其他对CuO [29] [30] 的相关研究,2.3 V~1.7 V对应于LixCuO (0 ≤ x ≤ 0.4),1.7 V~1.55 V,对应于LixCuO (0.4 ≤ x ≤ 0.8),1.45 V~1 V对应于LixCuO (0.8 ≤ x ≤ 2)。当放电电压达到1 V时,锂(x = 2)将CuO完全还原为Cu。相关化学方程式如下 [28] 所示:

首次从3 V至1 V放电:

CuO+Li + +e 1 2 Cu 2 O+ 1 2 Li 2 O (3)

1 2 Cu 2 O+Li + +e Cu+ 1 2 Li 2 O (4)

随后在电压范围为1到3 V之间的充放电过程:

Cu+ 1 2 Li 2 O 1 2 Cu 2 O+Li + +e (5)

1 2 Cu 2 O+ 3 2 Li 2 O Li 2 CuO 2 +Li + +e (6)

原始LTO样品、Cl-LTO-1:80样品和Cl-LTO-1:16样品在0.2 C、0.5 C、1 C、2 C和1 C的不同倍率下的放电容量如图3(d)所示。显然,无论在何种倍率下,Cl-LTO-1:16样品的放电容量都是最高的,其次是Cl-LTO-1:80样品,最后是原始LTO样品。随着倍率的增加,Cl-LTO-1:16样品的放电容量分别从243.5 mAh∙g−1 (0.2 C,第五周循环)持续下降至222.4 mAh∙g−1 (0.5 C,第十五周循环),190.1 mAh∙g−1 (1 C,第二十五周循环),155.2 mAh∙g−1 (2 C,第三十五周循环),190.6 mAh∙g−1 (1 C,第四十五周循环),而Cl-LTO-1:80样品的放电容量分别从173 mAh g−1 (0.2 C,第五周),163.4 mAh∙g−1 (0.5 C,第十五周),149.7 mAh∙g−1 (1 C,第二十五周循环),143.7 mAh∙g−1 (2 C,第三十五周循环),145.5 mAh∙g−1 (1 C,第四十五周循环)。当放电速率恢复到1 C时,Cl-LTO-1:16样品的放电容量几乎不变。结果表明,Cl-LTO-1:16样品具有良好的容量保持性。

Figure 3. (a) Charge-discharge cycling performance of pristine LTO, Cl-LTO-1:80 and Cl-LTO-1:16; (b) Charge and discharge curve of pristine LTO, Cl-LTO-1:80 and Cl-LTO-1:16 in the third cycle (0.2 C); (c) Charge and discharge curve of pristine LTO, Cl-LTO-1:80 and Cl-LTO-1:16 in the fifteenth cycle (1 C); (d) The rate performance of pristine LTO, Cl-LTO-1:80 and Cl-LTO-1:16

图3. (a) 原始LTO样品、Cl-LTO-1:80样品和Cl-LTO-1:16样品的充放电循环性能;(b) 原始LTO样品、Cl-LTO-1:80样品和Cl-LTO-1:16样品第三周充放电曲线(0.2 C);(c) 原始LTO样品、Cl-LTO-1:80样品和Cl-LTO-1:16样品第十五周充放电曲线(1 C);(d) 原始LTO样品、Cl-LTO-1:80样品和Cl-LTO-1:16样品倍率性能

3.3. 循环伏安法(CV)

Figure 4. Cyclic voltammograms of Cl-LTO-1:16 and pristine LTO

图4. Cl-LTO-1:16样品和原始LTO样品的循环伏安图

Cl-LTO-1:16样品和原始LTO样品在0.1 mV/s扫描速率下的循环伏安(CV)曲线如图4所示。循环伏安测试在1至3 V的电压范围内进行。Cl-LTO-1:16样品在1.5 V的阴极峰对应于放电期间将锂离子嵌入钛酸锂中。Cl-LTO-1:16样品位于1.699 V的阳极峰,对应于充电期间锂离子从钛酸锂中脱嵌。Cl-LTO-1:16样品和原始LTO样品之间的峰值差异分别为0.199 V和0.144 V。这表明,Cl-LTO-1:16样品的极化略大于原始LTO样品的极化。这是因为铜箔表面的CuO导电性差,导致欧姆极化增加,但掺杂Cl提高了LTO的电子/锂离子导电性,并在一定程度上降低了电化学极化,从而一定程度上弥补了欧姆极化带来的极化增加,导致虽然Cl-LTO-1:16样品的极化比原始LTO样品的极化略大,但不多甚至较为接近。Cl-LTO-1:16样品位于1.37 V的阴极峰,对应于Cu2O还原分解为Cu和Li2O。Cl-LTO-1:16样品位于2.68 V的阳极峰,对应于Cu2O和Cu,Li2O的转化反应生成Li2CuO2图4显示,与原始LTO相比,Cl-LTO-1:16样品中LTO的一对可逆氧化还原峰明显变宽。这表明,相对较高的Cl掺杂可以大大增加放电容量,并且Li4Ti5O12在此电压范围内的电化学反应过程没有改变。结果与图3中的放电曲线一致。

3.4. 电化学阻抗谱(EIS)

对原始LTO样品和Cl-LTO-1:16样品(13次循环后)进行电化学阻抗谱(EIS)测试,以进一步研究大量Cl掺杂对电子转移和离子扩散的影响。从图5可以看出,两个样品的曲线都由一个半圆和一条直线组成。高频区的半圆反映了电极中电荷转移引起的电荷转移电阻(Rct)。曲线和Z'轴交点到原点的距离对应于电解液、隔膜、集流体和集流体与正负电极之间界面的总阻抗所反映的欧姆阻抗(Rs)。低频区的直线反映了锂离子在电极材料中扩散引起的Warburg阻抗(ZW) [26] [31] [32] 。很明显,原始LTO样品的半圆比Cl-LTO-1:16样品的半圆形大。通过Zview软件拟合,Cl-LTO-1:16样品的电荷转移电阻为14.15 Ω,低于原始LTO样品(63.71 Ω),与Li+扩散系数 [3] [27] 相关的Warburg系数(Wo-T)为2.395 Ω,也低于原始LTO样品(7.751 Ω)。这一结果表明,Cl掺杂可以降低电荷转移电阻,使锂离子更容易扩散,归因于部分Ti4+还原为Ti3+以及掺杂Cl而导致晶格膨胀锂离子传输通道拓宽。此外,Cl-LTO-1:16样品的欧姆阻抗(Rs)为4.909 Ω,大于原始LTO样品(4.512 Ω)的欧姆阻抗。这是因为在铜箔表面形成的CuO,其导电性较差从而增加了欧姆阻抗,这与图4中的结果一致。

Figure 5. Electrochemical Impedance Spectroscopy (EIS) characterization of Cl-LTO-1:16 and pristine LTO

图5. Cl-LTO-1:16样品和原始LTO样品的电化学阻抗谱(EIS)表征

4. 结论

本研究采用传统的固相法在LTO中掺杂Cl,通过控制Cl的掺杂量制备了Cl-LTO-1:16和Cl-LTO-1:80两种样品。通过相关文献调研和XRD、SEM测试,发现在Cl-LTO-1:16样品中,电极材料和铜箔之间存在一个Li2O/CuO中间层,也可以提供相对较大的容量。Cl-LTO-1:16样品的放电容量显著高于Cl-LTO-1:80样品和原始LTO样品。容量增加的原因可以归结为两点,一是Cl取代O2−,导致晶格膨胀,离子通道拓宽以及Ti4+还原为Ti3+,从而提高了电子/离子电导率。这些因素使更多的氧化还原活性电位可以通过电化学方式获得,从而提高容量。二是Li2O/CuO复合材料贡献了部分容量,CuO具有较高的理论比容量,这就是为什么尽管Li2O/CuO活性材料的量很小,但它也可以提供较为可观容量的原因。

基金项目

国家重点研发计划(2021YFA1500900);国家自然科学基金(51876113);上海自然科学基金会(20ZR1422600)。

参考文献

NOTES

*通讯作者。

参考文献

[1] Zhang, H., Yang, Y., Xu, H., et al. (2022) Li4Ti5O12 Spinel Anode: Fundamentals and Advances in Rechargeable Batteries. InfoMat, 4, e12228.
https://doi.org/10.1002/inf2.12228
[2] Kong, D., Ren, W., Luo, Y., et al. (2014) Scalable Synthesis of Graphene-Wrapped Li4Ti5O12 Dandelion-Like Microspheres for Lithium-Ion Batteries with Excellent Rate Capability and Long-Cycle Life. Journal of Materials Chemistry A, 2, 20221-20230.
https://doi.org/10.1039/C4TA04711G
[3] Wu, F., Li, X., Wang, Z., et al. (2013) Petal-Like Li4Ti5O12-TiO2 Nanosheets as High-Performance Anode Materials for Li-Ion Batteries. Nanoscale, 5, 6936-6943.
https://doi.org/10.1039/c3nr02131a
[4] Nugroho, A., Chang, W., Kim, S.J., et al. (2012) Superior High Rate Performance of Core-Shell Li4Ti5O12/Carbon Nanocomposite Synthesized by a Supercritical Alcohol Approach. RSC Advances, 2, 10805-10808.
https://doi.org/10.1039/c2ra21653a
[5] Wang, L., Zhang, Y., Guo, H., et al. (2018) Structural and Electrochemical Characteristics of Ca-Doped “Flower-Like” Li4Ti5O12 Motifs as High-Rate Anode Materials for Lithium-Ion Batteries. Chemistry of Materials, 30, 671-684.
https://doi.org/10.1021/acs.chemmater.7b03847
[6] Ma, Y., Wang, Y., Yan, G., et al. (2022) Synthesis and Electrochemical Characteristics of Flower-Like Ca-Doped Li4Ti5O12 as Anode Material for Lithium-Ion Batteries. Powder Technology, Article ID: 117652.
https://doi.org/10.1016/j.powtec.2022.117652
[7] Hou, L., Qin, X., Gao, X., et al. (2019) Zr-Doped Li4Ti5O12 Anode Materials with High Specific Capacity for Lithium-Ion Batteries. Journal of Alloys and Compounds, 774, 38-45.
https://doi.org/10.1016/j.jallcom.2018.09.364
[8] Ncube, N.M., Mhlongo, W.T., McCrindle, R.I., et al. (2018) The Electrochemical Effect of Al-Doping on Li4Ti5O12 as Anode Material for Lithium-Ion Batteries. Materials Today: Proceedings, 5, 10592-10601.
https://doi.org/10.1016/j.matpr.2017.12.392
[9] Bai, Y.J., Gong, C., Qi, Y.X., et al. (2012) Excellent Long-Term Cycling Stability of La-Doped Li4Ti5O12 Anode Material at High Current Rates. Journal of Materials Chemistry, 22, 19054-19060.
https://doi.org/10.1039/c2jm34523d
[10] Chen, Y., Qian, C., Zhang, P., et al. (2018) Fluoride Doping Li4Ti5O12 Nanosheets as Anode Materials for Enhanced Rate Performance of Lithium-Ion Batteries. Journal of Electroanalytical Chemistry, 815, 123-129.
https://doi.org/10.1016/j.jelechem.2018.02.058
[11] Noerochim, L., Wibowo, A.T., Subhan, A., et al. (2022) Direct Double Coating of Carbon and Nitrogen on Fluoride-Doped Li4Ti5O12 as an Anode for Lithium-Ion Batteries. Batteries, 8, Article 5.
https://doi.org/10.3390/batteries8010005
[12] Rodriguez, E.F., Xia, F., Chen, D., et al. (2016) N-Doped Li4Ti5O12 Nanoflakes Derived from 2D Protonated Titanate for High Performing Anodes in Lithium-Ion Batteries. Journal of Materials Chemistry A, 4, 7772-7780.
https://doi.org/10.1039/C6TA01954D
[13] Kim, J.B., Lee, S.G., Choi, S., et al. (2019) Doping Behavior of Br in Li4Ti5O12 Anode Materials and Their Electrochemical Performance for Li-Ion Batteries. Ceramics International, 45, 17574-17579.
https://doi.org/10.1016/j.ceramint.2019.05.322
[14] Wang, Z., Yang, W., Yang, J., et al. (2020) Tuning the Crystal and Electronic Structure of Li4Ti5O12 via Mg/La Co-Doping for Fast and Stable Lithium Storage. Ceramics International, 46, 12965-12974.
https://doi.org/10.1016/j.ceramint.2020.02.066
[15] Li, Q., Xue, B., Tan, Y., et al. (2018) A Symmetrical and Co-Operating Effect of Mg-Zr Codoping on Li4Ti5O12 Anode Materials. Solid State Ionics, 326, 63-68.
https://doi.org/10.1016/j.ssi.2018.09.015
[16] Patat, S., Rahman, S. and Dokan, F.K. (2022) The Effect of Sodium and Niobium Co-Doping on Electrochemical Performance of Li4Ti5O12 as Anode Material for Lithium-Ion Batteries. Ionics, 28, 3177-3185.
https://doi.org/10.1007/s11581-022-04579-3
[17] Ding, S., Jiang, Z., Gu, J., et al. (2021) Carbon-Coated Lithium Titanate: Effect of Carbon Precursor Addition Processes on the Electrochemical Performance. Frontiers of Chemical Science and Engineering, 15, 148-155.
https://doi.org/10.1007/s11705-020-2022-x
[18] Jang, J., Kim, T.H. and Ryu, J.H. (2021) Surface Nitridation of Li4Ti5O12 by Thermal Decomposition of Urea to Improve Quick Charging Capability of Lithium-Ion Batteries. Scientific Reports, 11, Article No. 13095.
https://doi.org/10.1038/s41598-021-92550-z
[19] Liang, G., Pillai, A.S., Peterson, V.K., et al. (2018) Effect of AlF3-Coated Li4Ti5O12 on the Performance and Function of the LiNi0.5Mn1.5O4||Li4Ti5O12 Full Battery—An In-Operando Neutron Powder Diffraction Study. Frontiers in Energy Research, 6, Article 89.
https://doi.org/10.3389/fenrg.2018.00089
[20] Wang, Y., Zhang, W., Xing, Y., et al. (2021) Performance of Amorphous Lithium Phosphate Coated Lithium Titanate Electrodes with Extended Working Range of 0.01-3 V. Journal of Inorganic Materials, 36, 999-1005.
https://doi.org/10.15541/jim20200576
[21] Wang, Y., Ren, Y., Dai, X., et al. (2018) Electrochemical Performance of ZnO-Coated Li4Ti5O12 Composite Electrodes for Lithium-Ion Batteries with the Voltage Ranging from 3 to 0.01 V. Royal Society Open Science, 5, Article ID: 180762. https://doi.org/10.1098/rsos.180762
[22] Zhu, K., Gao, H. and Hu, G. (2018) A Flexible Mesoporous Li4Ti5O12-rGO Nanocomposite Film as Free-Standing Anode for High Rate Lithium Ion Batteries. Journal of Power Sources, 375, 59-67.
https://doi.org/10.1016/j.jpowsour.2017.11.053
[23] Jun, L., Huang, S., Li, S., et al. (2017) Synthesis and Electrochemical Performance of Li4Ti5O12/Ag Composite Prepared by Electroless Plating. Ceramics International, 43, 1650-1656.
[24] Yao, Z., Xia, X., Zhou, C.A., et al. (2018) Smart Construction of Integrated CNTs/Li4Ti5O12 Core/Shell Arrays with Superior High‐Rate Performance for Application in Lithium‐Ion Batteries. Advanced Science, 5, Article ID: 1700786.
https://doi.org/10.1002/advs.201700786
[25] Ping, W., Geng, Z., Jian, C., et al. (2017) Facile Synthesis of Carbon-Coated Spinel Li4Ti5O12/Rutile-TiO2 Composites as an Improved Anode Material in Full Lithium-Ion Batteries with LiFePO4@N-Doped Carbon Cathode. ACS Applied Materials & Interfaces, 9, 6138-6143.
https://doi.org/10.1021/acsami.6b15982
[26] Huang, Y., Qi, Y., Jia, D., et al. (2012) Synthesis and Electrochemical Properties of Spinel Li4Ti5O12xClx Anode Materials for Lithium-Ion Batteries. Journal of Solid State Electrochemistry, 16, 2011-2016.
https://doi.org/10.1007/s10008-011-1611-5
[27] Salvatore, K.L., Lutz, D.M., Guo, H., et al. (2020) Solution‐Based, Anion‐Doping of Li4Ti5O12 Nanoflowers for Lithium‐Ion Battery Applications. Chemistry—A European Journal, 26, 9389-9402.
https://doi.org/10.1002/chem.202002489
[28] Li, T., Ai, X.P. and Yang, H.X. (2011) Reversible Electrochemical Conversion Reaction of Li2O/CuO Nanocomposites and Their Application as High-Capacity Cathode Materials for Li-Ion Batteries. The Journal of Physical Chemistry C, 115, 6167-6174.
https://doi.org/10.1021/jp112399r
[29] Debart, A., Dupont, L., Poizot, P., et al. (2001) A Transmission Electron Microscopy Study of the Reactivity Mechanism of Tailor-Made CuO Particles toward Lithium. Journal of the Electrochemical Society, 148, A1266.
https://doi.org/10.1149/1.1409971
[30] Morales, J., Sánchez, L., Martín, F., et al. (2004) Nanostructured CuO Thin Film Electrodes Prepared by Spray Pyrolysis: A Simple Method for Enhancing the Electrochemical Performance of CuO in Lithium Cells. Electrochimica Acta, 49, 4589-4597.
https://doi.org/10.1016/j.electacta.2004.05.012
[31] Li, Y., Gao, H. and Yang, W. (2022) Enhancements of the Structures and Electrochemical Performances of Li4Ti5O12 Electrodes by Doping with Non-Metallic Elements. Electrochimica Acta, 409, Article ID: 139993.
https://doi.org/10.1016/j.electacta.2022.139993
[32] Guo, Z.P., Zhong, S., Wang, G.X., et al. (2003) Structure and Electrochemical Characteristics of LiMn0.7M0.3O2 (M = Ti, V, Zn, Mo, Co, Mg, Cr). Journal of Alloys and Compounds, 348, 231-235.
https://doi.org/10.1016/S0925-8388(02)00805-8