多维碳网络界面共价化学调控及其电化学储能研究

Multi-dimensional carbon network materials are typical carbon-based electrochemical energy storage materials. Tuning their interfacial structures and properties plays a key role in optimizing the efficiency in electrochemical reactions, and improving the performance of electrochemical energy storage devices. Covalent functionalization is able to introduce diverse chemical groups onto the surface of a material, and thus serves as an important strategy for interfacial tuning. In this project, in view of the high chemical inertness and the difficult interfacial modification of multi-dimensional carbon networks, in order to optimize the network and interfacial structures and improve the electrochemical energy storage performance, we will employ newly developed universal covalent functionalization reactions toward sp2 carbons to introduce atoms or organic functional groups onto carbon surface, improve the interfacial compatibility, add the electrochemically active cites, induce the formation of secondary carbon structures or composites, and achieve efficient structure control and interfacial modification. Based on the above carbon structure constructions, we will integrate these materials in electrochemical energy storage devices such as aluminum ion battery, combine diverse structure characterizations and electrochemical analytical techniques to study the effect of functional groups on the performance of electrochemical energy storage devices, and examine the relationship among network structure, interfacial properties and electrochemical performance as well as mechanism. According to the knowledge from these studies, we will optimize the synthesis routes of covalently functionalized multi-dimensional carbon networks to improve the total performance of electrochemical energy storage devices. The study is expected to provide important insights into the development of excellent carbon-based electrochemical energy storage materials.

多维碳网络材料是碳基电化学储能的代表性材料之一，调控其界面结构与性质，对优化其电化学反应效率、提高电化学储能器件性能具有重要意义。共价修饰法能够在材料界面引入多种化学功能基团，是界面改性的重要途径。本项目针对多维碳网络材料化学惰性较高、界面调控难等挑战，以优化材料的网络及界面结构、提高电化学储能性能为目标，采用对sp2型碳材料普适的新型共价方法引入原子或有机官能团，以期改善界面兼容性，增加电化学反应活性位点，诱导次级碳结构或复合结构的形成，最终实现多维碳网络材料的有效结构调控及界面改性。在此基础上，将该类材料应用于铝离子电池等电化学储能器件，综合结构表征及电化学分析技术，探索修饰基团等结构因素对电化学储能相关过程的影响规律，剖析网络结构-界面性质-电化学性能的相互关系及作用机制。据此优化多维碳网络材料的合成与改性路线，提升电化学储能器件的整体性能，为设计开发性能优越的碳基储能材料提供依据。

多维碳网络材料在电化学储能等领域应用广泛，其孔道和界面结构对电化学性能影响显著。碱金属还原法等普适性共价修饰方法，可在各类碳材料表面嫁接特定官能团以调控界面性质，结合孔道结构设计，可显著提升材料在储能器件中的性能。本项目结合多维碳网络结构构筑和碱金属还原修饰制备高性能碳材料，应用于铝-硫电池等储能器件中，揭示修饰基团等结构因素对电化学行为的影响规律，建立网络结构-界面性质-电化学性能的相互关系及作用机制。（1）探究了碱金属还原法共价修饰的影响因素和机理，发现不同Cu晶面对化学惰性的CVD石墨烯共价修饰的影响，指出压缩应力是影响石墨烯化学活性的本质原因，阐明压缩应力调控石墨烯化学活性的规律与机制。（2）设计制备了高比表面积、多级孔分布、高氮掺杂的三维多级孔碳材料，可作为硫的优良载体应用于铝-硫电池，显著提升了电池长循环稳定性，阐明了多级孔结构和氮掺杂界面对于硫的限域、电解液传输、电荷转移和电化学反应的影响机制。（3）制备了高比表面积的介孔石墨烯，并采用碱金属还原法在其表面修饰了吡啶官能团，作为硫的载体可显著提升铝-硫电池的放电电压并降低电压滞后。（4）开展了低温熔盐电解液设计和低温铝-石墨电池构筑、铝-硫族电池及关键材料的研究现状、挑战与展望、钠离子电池晶畴弥散分布SnPx/碳复合负极材料等研究和评述工作。基于上述工作，已发表或接收学术论文9篇，申请专利1项；培养博士研究生1名，硕士生8名（含3名硕士毕业生），其中1人获得“2019年硕士研究生国家奖学金”等多项奖励。这一系列工作为发展新型碳基储能材料和新型二次电池提供了重要参考。