站立式石墨烯超级电容器储能基础物性及双电层界面传质机理研究

Current practice of fabricating horizontal graphene-based supercapacitor electrode with chemical method owns the disadvantage of rapid restacking of graphene sheets during the dispersing, drying, and binding processes, which would strongly reduce the intersheet open channels and decrease the actual electrochemically accessible electrode surface area. This project proposed a novel supercapacitor electrode employing standing graphene as the energy storage active materials, owning the advantages beyond horizontal graphene counterpart in terms of avoiding interlayer restacking, improving active material wettability, as well as enhancing ion diffusion and charge transport, and potentially benefiting the energy storage performances. Experimental research will be conducted on the basic characteristics and capacitive behaviors of standing graphene with various morphologies and structures. Based on the classical thermodynamics and electrical double-layer theories, a comprehensive model on the standing graphene-electrolyte interfacial mass transfer mechanism will be built with coupling the macroscopic material wetting and microscopic charge transport, which will be used to explain the as-obtained capacitive behaviors of standing graphene and further provide pathways for energy storage performance optimization. The outputs of this project will be a beneficial supplement to the currently existed graphene based electrical double-layer theories, own the prospective meaning on the development of standing graphene based supercapacitors, and are expected to benefit the energy storage and related areas.

传统化学法制备的水平石墨烯极易在分散、干燥、粘结等环节中形成大量层间团聚，严重影响活性载体的有效储能面积和储能效果。本项目提出基于站立式石墨烯的新型超级电容器电极，可有效避免层间团聚、提高载体浸润、促进离子扩散和电荷转移，具有高效储能的潜力。项目将对具有不同形貌结构的站立式石墨烯活性载体开展全面的储能基础物性和储能性能测试，针对站立式石墨烯独特的形貌结构特点，基于热力学和界面双电层经典理论，充分考虑石墨烯层间浸润和电荷输运，从宏观到微观多层次耦合建立站立式石墨烯和电解液界面传质模型，对其储能特性进行解释并探索提高有效储能面积的途径，实现储能性能优化。项目成果将对现有石墨烯双电层电容理论形成有益补充，对站立式石墨烯超级电容器储能的发展具有前瞻性意义，有利于储能技术及相关领域的发展。

基于物理静电吸附原理，采用站立式石墨烯作为储能载体具有实现高性能储能的潜力。项目围绕石墨烯纳米通道形貌结构调控、石墨烯纳米受限空间内传质机理、纳米物理静电吸附储能性能优化等三个方面开展。通过改变等离子体参数，实现了站立式石墨烯纳米通道间距和高度等关键形貌结构参数的可控调整，建立了纳米通道形貌结构和储能性能的关联关系；结合分子动力学模拟及密度泛函理论等方法开展了多尺度计算，研究了电场作用下石墨烯纳米通道内流体流动及离子运动吸附规律，获得了纳米通道中载能粒子数密度分布规律及双电层储能微观结构，量化解析了纳米受限空间内多场耦合作用下的尺度效应和边缘效应，建立了站立式石墨烯-电解液双电层界面传质模型，开展了石墨烯通道内离子运动过程固态核磁共振检测，通过上述多尺度模拟和微观检测，获得了站立式石墨烯面向储能应用的形貌结构调控依据；研究了电解液离子及溶剂对储能性能的影响，针对溶剂分子极性作用开展了原子层级机理分析，强化界面电子输运并实现了储能性能提升。研究成果丰富了纳米尺度能质传递理论，为站立式石墨烯超级电容储能性能优化提供指导。项目全面完成了既定目标，发表SCI论文13篇，合著出版英文专著1部（Springer出版社出版）。作国际会议邀请报告2次，其中，受基金委推荐和科技部委派，作为我国7名代表之一赴印度班加罗尔参加首届金砖国家青年科学家会议并作邀请报告。所培养研究生获国家奖学金、希望森兰奖学金、美国空气奖学金等。项目负责人在项目执行期间晋升教授，获浙江省自然科学基金杰出青年基金等项目资助，并受邀担任SCI期刊Scientific Reports编委。