原子层沉积构筑三维导电碳骨架/无机复合气凝胶及其电化学储能研究

Carbon aerogels, as novel three-dimensional (3D) carbon-based nanostructures, have special 3D cross-linked conductive networks and hierarchical porous structures. Carbon aerogels are more and more attractive to be used as conductive scaffolds of composite electrode materials in the devices of electrochemical energy storage, without any additional binders. However, it is a great challenge to fill other active materials into the pores of carbon aerogels. The traditional methods for preparing carbon/inorganic hybrid aerogels are very difficult to coat the carbon scaffolds uniformly, or may damage the cross-linked frameworks and then decrease the conductivity and mechanical strength. Here we propose a novel strategy to utilize atomic layer deposition (ALD) for the construction of 3D conductive carbon/inorganic hybrid aerogels for electrochemical energy storage. The ALD method will be used to evenly fill active materials into the nanopores of carbon aerogels for improving the dispersibility and storage capacity. Moreover, active materials with different components, especially multiple compounds and multilayer-stacked films, will be deposited in the carbon aerogels to enhance the cycle life and stability of the composite electrodes. Furthermore, the relations between the electrochemical performances and the components, micro-scale structures and surface states of hybrid aerogels will be investigated. We will also illustrate the mechanisms about how the electrochemical redox and ion insertion/extraction processes of active materials are occurred with the effects of conductive carbon scaffolds. By carrying out this project, new rules and principles to design and construct novel mesoporous composite electrode materials for supercapacitors (pseudo-capacitors) and secondary batteries will be established.

碳气凝胶作为新型三维碳基纳米结构，具有独特的三维交联导电网络和多级孔道，非常适用于充当电化学储能器件中复合电极材料的导电骨架，且无需添加粘结剂，受到了广泛关注。而如何将其它电化学活性材料均匀填充进碳气凝胶的孔隙中，成为一个新的难题。传统方法难以在碳骨架上形成均匀包覆，或可能破坏其三维交联结构，降低其电学和力学性能。本项目提出以原子层沉积方法构筑三维导电碳骨架/无机复合气凝胶用于电化学储能的新思路，在碳气凝胶孔隙中均匀填充电化学活性材料，提高其分散性和储能容量；同时进一步调变活性材料的组分，进行多元化合物沉积和多层薄膜交替沉积，避免三维交联结构在充放电时被破坏，提高电极材料的寿命和稳定性。探讨复合气凝胶的成分、微观结构、表面性质与电化学性能的关系，阐明不同活性材料利用导电碳骨架进行氧化还原和离子嵌脱过程的作用机理，为探索新型介观多孔复合电极材料在赝电容和二次电池中的应用提供规律性结果。

本项目面向未来新能源汽车和便携式电子产品对高能量密度二次电池器件和柔性可穿戴储能器件的迫切需求，开发高能量密度的三维交联电极材料、柔性锂硫电池和超级电容器。通过原子层沉积制备了三维交联结构的复合电极材料，结合良好的机械性能、高容量和突出的化学和电化学稳定性等优势，实现比容量、安全性和柔性的兼顾，提高便携化学电源系统的比能量和比功率，提升储能器件的柔性化、轻量化、安全性和适用性水平。本课题的开展结合能源化学、材料学、物理化学、计算化学等多个学科，深入研究复合电极材料的成型机理及调控规律，阐明柔性电极结构对提升高载硫电极电化学性能的规律，揭示柔性储能器件动态电化学反应机理，为柔性储能器件的设计提供科学依据。该项目将有助于完善我国在储能器件前沿研究的战略布局，提高原始创新领域的核心竞争力。