原位制备自由基聚合物/石墨烯复合电极材料及其性能优化

Sustainable TEMPO-bearing radical polymers with excellent electrochemical stability and high rate performance have been recently the focus of the organic electrode materials research, by which the substitution of conventional inorganic electrode materials offers a promising alternative for the next generation of rechargeable batteries. However, the low intrinsic conductivity and solubility in the electrolyte of radical polymers hindered their battery application in rate performance and cycling stability. The incorporation of radical polymers with carbon nanomaterials shows an effective approach to improve the electrical conductivity of the electrode materials with inhibited dissolution of the active materials. In our previous study, several covalent functionalization strategies of radical polymers onto the surface of graphene sheets were developed to suppress their dissolution in the electrolyte and enhance the electrical conductivity of the electrode materials, which show improved rate performances and cycle stabilities. Meanwhile, the oxygen-containing groups of the graphene oxides show reversible redox reaction during the charge/discharge process, which resulted in the composite organic electrodes with multiply energy storage mechanisms. In this current proposal, we design an optimized in situ polymerization of the monomer onto the surface of graphene to directly prepare nanocomposite electrodes without tedious post-assemble process. During the in situ polymerization, radical polymers will be directly incorporated into the matrix of the conductive graphene sheets at “molecular” levels with highly uniform homogeneity, which lead to a shorter conduction pathway and, thus, performance improvement. The different oxygen functionalities content of graphene oxide and the ratio of radical polymer to graphene will also be tested in order to get an optimized formula of the composite organic electrode with high electrical conductivity and maximized active materials content. The successful implementation of this proposal will shed light on the development of lithium-organic batteries based on radical polymers with high rate performances and long life cycles.

含有TEMPO的自由基聚合物具有循环稳定、倍率性能高及原料易得等优点，近年来备受关注。但是，其固有的低导电性及在电解液中较高的溶解度限制了自由基聚合物电极材料的倍率性能和循环稳定性。与碳纳米材料形成复合电极材料是解决上述问题的有效途径。前期研究中，我们发展了多种将自由基聚合物接枝在石墨烯表面的方法，获得了具有良好循环稳定性和倍率性能的自由基聚合物/石墨烯复合电极材料，同时石墨烯表面氧官能团也可以参与能量存储。本项目中，我们将优化电极材料的制备和组成，通过原位聚合直接制备“分子”水平上均匀分散的自由基聚合物/石墨烯复合材料，减少电极组装过程对材料界面均一性的影响，提高电荷传递效率；通过对石墨烯表面含氧基团的含量以及自由基聚合物/石墨烯的比例调控，提高材料的导电性，增加活性物质的含量，获得具有优良倍率性能和循环稳定的有机电极材料，为发展高性能有机锂电池提供新的思路。

将有机电极材料与碳纳米材料相结合，是提高有机电极材料导电性和抑制其在电解液中溶解的有效手段。将聚合物电极材料接枝在碳纳米材料的表面可以有效的提升材料的性能。本项目中，我们发展了原位自由基聚合制备了自由基聚合物/碳纳米复合材料的方法，研究了这类复合材料作为正极材料时在锂离子、钠离子电池上的应用，并初步阐明了其在储能过程中的结构与物质变化规律。我们所发展的原位自由基聚合表面接枝的策略，可以方便高效地制备碳纳米材料表面接枝自由基聚合物复合电极材料，并且通过条件优化，我们可以得到具有双氧化还原反应的电极材料，提高了电极的比容量，为发展高性能有机电极材料提供了新的思路。我们针对有机电极材料比容量低和电压平台低的问题，结合有机化学与材料化学，利用简单高效的化学反应，发展了多种性能优异的有机电极材料，并用于有机锂离子电池、钠离子电池等，得到了很好的结果。本项目的研究成果将有助于推动有机电极材料的发展，为新一代电池技术的发展提供有意义的探索。