石墨烯桥联聚噻吩包覆的锗纳米颗粒的三维多孔锂离子电池复合负极材料的研究

Germanium has been considered as promising alternative anode materials for high capacity Lithium-ion batteries ( LIBs ) due to its high theoretical gravitational and volumetric capacity（1600 mAh/g and 8500 mAh/cm3）. But Germanium suffers significantly large volume changes during Li-ion insertion and extraction processes, which leads to pulverization of the electrodes and degrades the capacity of anode materials consequently. In this project, 3D porous anode materials of graphene interconnected with germanium nanoparticles wrapped by high conductive Poly(3,4-Ethylenedioxythiophene)(PEDOT) are designed. The aim is to address the pulverization problem of Ge through constructing Germanium -based three dimensional porous conductive networks with good elasticity by hybridizing Ge nanoparticles, PEDOT coating and 2D graphene. The study will focus on the control of homogeneity and interfaces inside Ge@PEDOT/RGO composite materials. The corresponding relationship between preparation conditions, structure and electrochemical properties will be studied. The interface change during the Li-ion insertion and extraction processes will be revealed and their synergistic mechanism on the Ge pulverization will be clarified. The success of the project will provide support for the development of high capacity Lithium-ion batteries. And it will provide reference for the development of other anode materials with high capacity.

锗对锂离子具有高的理论质量比容量(1600mAh/g)和体积比容量(8500 mAh/cm3)，是高能量锂离子电池非常具有发展前景的负极材料。但是，锗负极材料在脱嵌锂过程中会发生大的体积变化，导致负极材料粉化容量衰减。本项目设计了一种氧化还原石墨烯(RGO)桥联聚噻吩（PEDOT）包覆的锗纳米颗粒的三维多孔结构锂离子电池复合负极材料（Ge@PEDOT/RGO），旨在通过采用纳米化的锗颗粒、聚噻吩包覆和二维石墨烯联合构筑锗负极的弹性多孔三维导电骨架，解决锗粉化导致的导电结构破坏问题。本项目重点研究该复合材料均匀性及其界面的控制方法，研究制备工艺、结构和电化学性能之间的关系，揭示各级界面在锗负极脱嵌锂过程中的变化规律，发现其抑制锗负极粉化的协同作用机制。项目的成功，可为高能锂离子二次电池研发奠定技术基础，对其他高容量锂离子电池负极材料的发展也具有借鉴作用。

锗对锂离子具有高的理论质量比容量和体积比容量，是高能量锂离子电池非常具有发展前景的负极材料。但是，锗在脱嵌锂过程中发生粉化导致导电结构破坏容量衰减，大大限制了锗负极材料的实用化，构筑并维护高强度的导电骨架是抑制锗负极粉化的有效途径。本项目围绕高导电性和高机械强度的三维多孔连通导电骨架的设计和构筑，从纳米化活性物质出发，采用物理混合法、原位法等将聚噻吩和石墨烯等微纳碳结构引入导电骨架中，成功制备了包括氧化还原石墨烯桥联聚噻吩包覆的锗纳米颗粒在内的多种结构新颖电化学性能优良的三维多孔导电骨架负极材料 (Ge@PEDOT/RGO，Ge@PEDOT、Ge@ G 、Ge@HCS-rGO 、3D-GPNS/Ge、MOFs@ Ge等）。研究了合成工艺对负极材料结构的影响，实现了其界面和均匀性的调控，获得了具有高放电容量、优良循环稳定性和倍率性能的负极材料，0.2C放电容量达到2117.3 mAhg-1,循环200次后容量达到958.6 mAhg-1，4C时放电容量达到1010.0 mAhg-1。研究了三维多孔导电骨架组成、结构与其电化学性能之间的内在联系，分析了界面结构脱嵌锂过程中的变化规律，明确了三维多孔导电骨架的组成、高电导性和三维多孔连通网络抑制锗负极粉化的协同作用及其机制，为高容量和优良循环性能的新型电极材料导电骨架的规律性设计和构筑提供了理论指导，对新型高能锂离子二次电池研发具有重要意义。项目资助发表高水平SCI论文5篇，申请国家发明专利 9项，授权6项，进行国际学术会议交流1次，项目主持人获军队科技进步二等奖1项。培养硕士研究生5人，其中4人已经取得硕士学位，1人在读，1人获国家奖学金奖励。项目资助经费53万元，支出26.618852万元，剩余经费26.381148万元，剩余经费计划用于本项目研究后续支出。