一维核（Si、Ge）/壳（碳）结构多孔纳米线、纳米管的可控制备以及高性能储锂研究

Substantial efforts have been made in the last decade to replace the carbonaceous anode (theroratical capacity 372 mAh/g) material in Li-ion batteries (LIBs) by alternatives allowing a high Li-storage capacity. In terms of energy capacity, M-based materials (M=Si、Ge) are far ahead of other metals or metalloids, with over 4200 mAh/g and 1600 mAh/g capacity, respectively. However, practical application using M-based materials are hampered by their poor cycling stability. This problem is attributed to the significant volume changes and low electronic conductivity. The proposed research plan will focus on develop electrospinning process to fabricate 1D porous core (Si, Ge) /shell (carbon) nanowires and nanotubes with controllable morphology to overcome these challenges and develop LIBs with excellent stable cyclability and high power densities. This project will significantly help us clarifying the following fundamental and practical issues: the intrinsic principle of structure change during charging/discharging process, the mechanism M-based composite materials as anodes for LIBs. The technology developed under this grant will help fill the need for next generation high energy density power sources.

便携式电子设备及电动汽车的高速发展，迫切需要开发新型高比容量锂离子电池。Si、Ge 作为锂离子电池负极材料分别具有4200mAh/g 和1600mAh/g 的理论容量，已成为替代传统的石墨类材料（理论容量372 mAh/g）的最佳负极材料。然而，此类电极材料由于受体积效应及低电子电导的限制难以实际应用。本项目着眼于抑制合金储锂负极材料的体积效应、提高材料电子电导率，从低维化、纳米化、多孔化、导电包覆等方向对Si、Ge 进行改性。发展静电纺丝法，可控制备一维核(Si、Ge) /壳（碳）结构多孔纳米线、纳米管（直径、壁厚、孔径、碳包覆层厚度均分别可控），筛选兼具大储锂容量、长循环寿命和高倍率性能的负极材料。深入研究一维核/壳结构多孔纳米线、纳米管的电化学储锂过程，明晰材料在脱、嵌锂过程中结构的变化规律，研究其脱、嵌锂历程和电化学储锂机理,为下一代锂离子动力电池的研制提供实验与理论支持。

Ge/C 纳米线具有一维材料短的离子传输距离、高的接触面积等优势。同时多孔的碳包覆结构有利于提高复合材料的电子电导和有利于电解液的浸润。从而得到电化学性能优异的Ge/C复合锂离子电极材料。同时，我们还利用静电纺丝技术制备了Ge/C纳米纤维复合电极材料，在优化实验条件获得了具有高的比容量和优异的电化学电极性能的电极材料。在项目执行期间，我们还将这种一维结构的电极材料的设计思路扩展到制备其他类电极材料的制备过程中，通过优化实验条件取得了相关的基础研究结果。本项目在Angew. Chem. Int. Ed, Adv. Mater., Adv. Energy. Mater, ACS Nano, Adv. Funct. Mater., Small 等杂志上发表SCI论文50篇。其中，我们利用室温氧化还原自组装法，成功制备出由纳米线组成的三维纳米织构的V6O13电极材料，并将该材料应用在高能量密度锂离子电池中，取得了优异的电化学性能。该成果以“3D V6O13 Nanotextiles Assembled from Interconnected Nanogrooves as Cathode Materials for High-Energy Lithium Ion Batteries”为题发表在《纳米快报》上(Nano Lett. 2015, 15, 1388−1394)。在文章出版后，在国际权威期刊《Advanced Energy Materials》在线发表了一篇题为“Recent Progress in the Applications of Vanadium-Based Oxides on Energy Storage: from Low-Dimensional Nanomaterials Synthesis to 3D Micro/Nano-Structures and Free-Standing Electrodes Fabrication”的综述文章中高度评价了这篇工作。该工作为高性能锂电池电极材料的设计和制备提供了新思路。