高比容量空洞结构电极材料的构筑及其超电容性能

Low energy density and rate capability is one of the bottleneck problems for the development of supercapacitor. In order to improve the specific capacitance of supercapacitor electrode, and simutanelusly promote the ion transport in the interior of electrode materials, the basic building blocks of manganese oxide and graphene nanosheets with hole structure on their 2D basal planes will be prepared by a sereis of controlled methods including acid treatment with NH4HSO4, SiO2 template mosaic and the delamination/oxidation of the oxide precursors, and also the chemical hole mechanism of these nanosheets will be investigated. With these hole nanosheets as buidling blocks, the hole-structured electrode materials will be designed and fabricated by using both a flocculated-freezing drying technology and a free-standing nanosheet assembling technology on the basis of controlling the hollowing rate, the assembly methods and component content, and a new fabricating technology for the electrode materials with large power and high energy density will be developed. By systematically investigating the electrocapacitive performance of the composite electrodes with cyclic voltammetry, constant current charge-discharge and electrochemical impedance spectroscopy, the relationship between structure and capacity of the prepared electrode materials will be demonstrated and the influence of the hole structure on the ion transport and the specific energy of the electrode materials will also be researched. In addition, based on the chemical doping, mass ratio optimization and the assembling supercapacitor, the role of the hole structure in improving the performance of the assembled supercapacitor will be investigated. It is anticipated that the hole structure not only provide channels for fast ion transport, but also maximize the utilization of both electrichemical double layer capacitance and pseudocapacitance. The research results might open opportunity for resolving the key issue of the current supercapacitors that are characterized by their low energy desity. This study will promote the advance of inorganic material chemistry, energy storage materials and the other fields.

能量密度低及倍率性能是制约超级电容器发展的瓶颈问题之一。本项目从提高电极材料比容量和促进离子快速传递出发，通过NH4HSO4酸处理、SiO2模板镶嵌及剥离/氧化等技术，制备空洞结构氧化物纳米层（如MnO2和V2O5）和石墨烯纳米层，阐明氧化物纳米层空洞化化学机制；采用絮凝聚沉-冷冻干燥及自支撑层组装等手段，制备纳米层空洞化率、组装方式和组分含量可控空洞结构纳米电极材料，开发高能量密度和大倍率超级电容器用电极材料制备新技术；通过交流阻抗等技术，阐明空洞结构对电极离子传输及材料比能量的影响规律，为设计结构与性能可控空洞结构电极材料提供依据；通过层板化学掺杂、电极质量优化及电容器组装等手段，研究空洞结构材料对实际电容器能量密度和功率密度的影响，期待实现双电层和赝电容双重存储机制的同时发挥，解决超级电容器电极材料大功率下比能量密度低等突出问题。研究将促进无机材料化学和储能材料等领域的进步。

超级电容器是重要的储能器件，其性质主要由电极材料决定。制约超级电容器发展瓶颈问题是如何实现高功率密度下的高能量密度。要实现超级电容器快速储存能量和大功率密度下的高能量密度，在拥有高比容量前提下如何实现材料结构中离子的快速传输是需要解决的主要问题之一。4 年来课题从提高电极材料比容量、促进离子快速传递及电极材料柔性与电容性能平衡优化出发，通过孔洞结构纳米层制备，孔洞结构纳米层组装柔性薄膜及纤维电极材料及柔性全固态超级电容器组装及性能评价等方面开展工作，取得主要研究结果如下：（1）开发了原位氧化还原制备多孔二氧化锰纳米层孔洞化新技术和柔韧性好、高堆积密度和高质量比电容石墨烯纳米层孔洞化新技术，实现了电极材料倍率性能的有效改善，纳米层孔洞化处理是解决电解质离子在纳米层垂直方向传输的有效手段，为开发高比容量下的高倍率性能超级电容器电极材料提供了方法学，为改善超级电容器高能量密度下的倍率性能稳定奠定了基础；（2）利用静电纺丝技术及湿法纺丝技术及孔洞纳米层自组装等方法，发展了高柔性及大容量柔性超级电容器用纤维及薄膜电极材料及高柔性、高能量密度全固态柔性纤维超级电容器组装新技术，不仅为组装高容量、柔韧性好及能量密度高全固态纤维超级电容器提供了基础材料，而且为解决全固态柔性电极材料柔性与电容的优化平衡提供了方法学；（3）发展了改善现有碳基柔性超级电容器电极材料比容量低及组装器件能量密度低等突出问题新方法，为制备高柔韧性、大比容量柔性超级电容器用电极材料提供了新途径。这些研究阐明了孔洞结构对电极离子传输及材料能量密度与功率密度平衡的影响规律，为设计结构与性能可控孔洞结构电极材料提供了依据，实现了双电层和赝电容双重存储机制同时发挥下的电极材料柔性与容量优化平衡，解决了柔性超级电容器电极材料大功率下比能量密度低等突出问题，促进了储能材料及其器件的进步。