新型醌类聚合物电极材料的合成及性能研究

Quinones are believed to be one of the most promising organic lithium-storage electrodes. However, the conventional small organic molecules, such as benzoquinone, naphthoquinone, anthraquinone, cannot be used directly in common rechargeable Li batteries with non-aqueous electrolytes due to their serious dissolution in electrolytes, which decreases their discharge/charge stability and results in poor cycle life. The incorporation of the quinone unit into a polymer is an effective approaches to improve the stability. In this project, a series of novel benzoquinone(s) containing norbornene (NBE) derivatives will be synthesized through rational molecular design, which are further polymerized through ring opening metathesis polymerization (ROMP). The design of monomer structure follows two principles: (1) minimizing the introduction of non-active group; (2) multiple benzoquinone units share a NBE skeleton. The polymerization behavior of these novel benzoquinones containing monomers using three generation Grubbs catalysts will be investigated systematically. The performance of these monomers and corresponding polymers as electrode materials will be studied as well. With this project, it is promising to obtain novel quinone(s) containing polymeric electrode materials with high gravimetric capacity (250-400 mAh/g) and long-term cycling stability, which may have positive impact on the development of large scale and low cost energy storage materials and technology.

醌类化合物被认为是一类极具发展潜力的锂离子电池有机电极材料。但普通小分子醌类化合物易溶于电解质，电极材料的流失会造成电池的充/放电循环稳定性大大降低。将醌式结构引入到聚合物中是提高循环稳定性的有效方法，本项目拟设计合成系列含有苯醌基元的新型降冰片烯(NBE)衍生物，再通过开环易位聚合(ROMP)方法催化聚合得到系列新型高分子量醌类聚合物电极材料。为提高比容量，单体分子设计将遵循两个原则，一是尽量减少非活性基团比例，二是在一个NBE骨架上引入多个苯醌结构。本项目将系统探究这些单体在不同Grubbs催化剂催化下的开环易位聚合行为。对比研究这些新型单体以及相应醌类聚合物在锂离子电池电极应用中的比容量、循环稳定性、充放电效率(库仑效率)、氧化还原电势等性能。通过本项目，有望得到系列高比容量(250-400 mAh/g)和高循环稳定性的有机电极材料，对发展大规模、低成本储能材料与技术具有积极意义

有机电极材料具有资源丰富、成本较低及环境友好等优点，是一类非常具有应用前景的二次电池电极材料。本项目主要针对醌类小分子电极材料易溶解于液体电解质的问题，提出了活性基元高分子化等多种抑制其溶解的策略，大幅提升了醌类有机电极材料的循环稳定性等电化学性能。（1）系统地研究了聚合物的分子量大小及电极制备方法对聚合物电极材料电化学性能的影响。研究发现虽然高分子量聚合物的溶解性会大大降低，但是高分子量聚合物难以分散，给均匀电极的制备带来困难。本项目提出了优化电极制备方法和优化聚合物分子结构等方法有效改善了聚合物电极的电极微结构，有效提升了材料的电化学性能；（2）提出了近平面的寡聚物活性分子设计理念。近平面结构的寡聚物兼具有小分子易分散和聚合物难溶解的优点，所设计合成的苯醌基有机材料的比容量和循环稳定性都显著提升，其中优化的分子超过了目前已报道的所有苯醌类小分子和绝大多数苯醌基聚合物电极材料；（3）在国际上首次将原位电聚合方法应用于锂离子电池有机电极的制备，巧妙地解决了小分子易溶解和聚合物难分散的难题，所用模型分子可稳定循环5000圈以上。