高强多孔石墨烯基杂化纤维及其柔性/微型高效锂离子电池的研究

Graphene fibers with excellent mechanical, electrical and electrochemical properties and good flexibility are very suitable for the preparation of fiber-shaped flexible energy storage devices. Currently, graphene fibers are mainly used to fabricate flexible supercapacitor with low energy density, no research effort has been devoted to graphene fiber-based lithium-ion batteries which are expected to meet the special needs of wearable electronics and smart clothing. Limited by the nature of graphene as well as their restacking problem, pure graphene fiber-based energy storage devices usually have low capacitance, which greatly limits their practical applications. To address these problems, in this project we intend to employ two methods to introduce active materials into graphene fiber to fabricate high-performance composite fiber electrodes and study the interactions between active materials and graphene.Then we assemble the obtained composite fibers into continuous and stable fiber-shaped lithium ion battery and study the influences of the composition and structure of the electrode on the battery. Finally, we weave the obtained flexible lithium-ion battery into fabric and explore their potential application in the wearable electronic devices.

石墨烯纤维具有优异的力学、电学和电化学性能以及良好的柔性，是设计组装线状柔性储能器件的关键电极材料。目前研究主要集中在低能量密度的线状超级电容器方面，但在高能量密度的线状锂离子电池领域尚无报道，而后者非常有望满足可穿戴电子和智能服装供电的特殊紧迫需求。受限于石墨烯自身物理性质以及易自堆积等问题，纯石墨烯纤维作为锂电池负极的比容量较低，且不能作为锂电池正极，仅依靠纯石墨烯纤维无法满足线状柔性锂电池的应用要求。针对以上问题，本项目拟通过纺前杂化（一步法）和纺后杂化（两步法）向石墨烯纤维中引入高比容量的正/负极活性物质，研究活性物质与石墨烯之间界面相互作用规律，得到长度连续、强度较高、比容量大的杂化纤维正/负极。将杂化纤维正极和负极组装成稳定的线状锂离子电池，系统研究电极组成和结构对电池性能的影响规律。最后通过编织、缠绕等方式进一步获得织物状和可拉伸的锂离子电池，探索其在可穿戴电子和智能服装中。

近年来，随着可穿戴设备的发展，大量的智能设备，如柔性显示器、柔性传感器、智能眼镜和手表等，被广泛应用，因此亟需开发柔性可弯折且高效率的智能储能器件为以上功能器件提供能量支持其稳定运行。在各类储能设备中，锂离子电池因具备高能量密度、无记忆效应以及长循环寿命的特点而受到大量关注，有望在柔性储能领域大放异彩。但固有的刚性结构电极大大限制了其在可穿戴系统的应用，因此需要开发纤维状电极以期满足柔性的需求。石墨烯纤维是由石墨烯纳米片经过湿法纺丝片片堆叠而成，由于其本身具有优异的力学性能、电学性能、热稳定性能以及高的比表面积，因此可以满足柔性锂电对电极材料的要求。但石墨烯纤维在纺丝过程中往往存在严重的π-π堆叠结构，因此需通过第二组分杂化的方式提高电极材料的电化学性能，本项目通过“一步法”和“两步法”的方式分别构建石墨烯杂化纤维，并研究纺丝参数、第二组分表面化学特性及界面属性对纤维结构的影响，构建可用于纤维状锂离子电池等储能器件的柔性电极，系统研究了其力学、电学和电化学性能，并进一步探索了织物状器件在智能可穿戴设备中的应用。