In situ self-nucleophilic synthesis of nano-Li_(4)Ti_(5)O_(12)/reduced graphite oxide composite with mesopore-oriented porous structure for high-rate lithium ion batteries  

基于亲核活性机理合成具有优良高倍率性能的纳米Li_(4)Ti_(5)O_(12)/还原氧化石墨介孔复合负极材料

作　　者：PAN Feng-ling MING Hai CAO Gao-ping ZHANG Ting-ting ZHANG Wen-feng XIANG Yu 潘凤玲;明海;曹高萍;张婷婷;张文峰;向宇(Research Institute of Chemical Defense,Beijing 100191,China;Beijing Key Laboratory of Advanced Chemical Energy Storage Technology and Materials,Beijing 100191,China;School of Chemical Engineering,Beijing University of Chemical Technology,Beijing 100029,China)

机构地区：[1]Research Institute of Chemical Defense,Beijing 100191,China [2]Beijing Key Laboratory of Advanced Chemical Energy Storage Technology and Materials,Beijing 100191,China [3]School of Chemical Engineering,Beijing University of Chemical Technology,Beijing 100029,China

出　　处：《Journal of Central South University》2022年第9期2911-2929,共19页中南大学学报（英文版）

基　　金：Project(21875283) supported by the the National Natural Science Foundation of China。

摘　　要：It is the core to improve the electron/ion transfer features of Li_(4)Ti_(5)O_(12) for achieving high-rate anode in lithium ion batteries.By directly using graphite oxide powder,nano-Li_(4)Ti_(5)O_(12)/reduced graphite oxide composite with mesopore-oriented porosity is prepared through one-pot facile ball-milling method in this work.Synthesis mechanism underlying the self-nucleophilic effect of oxygen-containing functional groups in graphite oxide is substantiated.Reactants can intercalate into graphite oxide bulk and in-situ generate nanoparticles.Subsequently,graphite oxide with nanoparticles generated inside can obtain a mesopore-oriented porous structure under ball-milling.Furthermore,the synergistic effects of Li_(4)Ti_(5)O_(12) nanoparticles and mesopore-oriented porosity strengthen composites with rapid Li^(+)diffusion and electron conductive frameworks.The obtained optimal LTO/GO-1.75 composite displays excellent high-rate capability(136 mA·h/g at 7000 mA/g)and good cycling stability(a capacity retention of 72%after 1000 cycles at 7000 mA/g).Additionally,the reactants concentration in this demonstrated strategy is as high as 30 wt%−40 wt%,which is over 6 times that of traditional methods with GO suspensions.It means that the strategy can significantly increase the yield,showing big potential for large-scale production.改善Li_(4)Ti_(5)O_(12)电子和离子的传导性能是提高其倍率性能的关键。本文利用氧化石墨的亲核反应活性,采用简易的一锅法制备了具有优良倍率性能的纳米Li_(4)Ti_(5)O_(12)/还原氧化石墨介孔复合材料。理论计算和实验结果证实氧化石墨中含氧官能团具有强亲核反应活性,是获得纳米Li_(4)Ti_(5)O_(12)颗粒和介孔结构的关键,揭示了基于亲核活性的材料合成机理。在复合材料制备过程中,反应物嵌入氧化石墨本体,并在层间原位形成Li_(4)Ti_(5)O_(12)前驱体纳米颗粒。所形成的前驱体纳米颗粒会增大氧化石墨层间距,并进一步减弱其层间作用力,导致氧化石墨在随后的球磨作用下被剥离为介孔结构。经高温烧结,成功制备纳米Li_(4)Ti_(5)O_(12)/还原氧化石墨介孔复合材料。纳米颗粒与介孔结构的协同效应使得复合材料具有高Li^(+)扩散速率和高电子电导率,进而提高复合材料倍率性能。其中,最佳配比的LTO/GO-1.75复合材料具有优异的高倍率能力(7000 mA/g下的可逆比容量达136 mA·h/g)和良好的循环稳定性(7000 mA/g下循环1000次后容量保留率为72%)。不仅如此,该合成方法中的反应物浓度高达30 wt%~40 wt%,是传统氧化石墨烯悬浮液制备方法的6倍以上,意味着本合成方法具有较高的复合材料产率,具有实用化生产的潜力。

关 键 词：graphite oxide nucleophilic catalysis Li_(4)Ti_(5)O_(12) high rate anode 

分 类 号：TB332[一般工业技术—材料科学与工程]