储能应用导向的石墨烯-石油基多级孔纳米碳材料的制备

Both petroleum and graphite are cheap carbon resources, but their clean usage is really a task. Recently, we have progressed on the preparation of large literal sheet size of graphene flakes with ultrahigh thermal conductivity at high yield and on the conversion of cellulose or pitch onto graphene into featured carbon materials applied for high-performance supercapacitor and lithium sulfur battery. As we suggested, this project will aim at rational synthesis of hierarchically porous graphene-carbon materials using petroleum precursors (such as petroleum pitch) at the presence of graphene to apply for electrochemical energy storage. Because graphene has very high thermal and electrical conductivity as well as only surface but no bulk, in principle, graphene can stimulate the activation of aromatic molecules of pitch converted into porous carbon at lower temperature with energy saving. There is big volume difference between graphene and organic macromolecule or polymer upon thermal annealing, which can result in rich mesopores of activated carbon grown on graphene. We’ll systematically study the factors on the targeted carbon materials, including the control of the ratios of petroleum and graphene, the voids of graphene nanomeshes, the condition of thermal activation of petroleum onto graphene. We’ll rationally adjust the size, quality and quantity of graphene as well as carbon pore size for the new carbon material to reveal the integrating effects of graphene and activated carbon on energy storage. We’ll explore nitrogen-doped and sulfur-doped porous carbons with the atomic economy of the petroleum with the maximum of the production rate of pitch into carbon materials for Li-S ion battery. The key fundamental question to be solved in the project is the mechanism of graphene stimulating the chemical activation of petroleum pitch conversion into hierarchical porous graphene-carbon materials. We are planning to use in-situ TGA-IR/Raman-mass spectroscopies and in-situ TEM annealing to track the process of petroleum activation at the presence of graphene. We’ll control the microstructures and morphology, pore size distribution, electrical conductivity, electrolyte electrowetting of the carbon material to meet the requirement of high-performance of electrochemical energy storage. The project, if approved, should be useful to develop the key technology from petroleum into high-performance electrochemical energy storage.

石油与石墨都是丰廉的碳资源，但其洁净应用任重道远。申请人在取得高导热率石墨烯的制备以及石墨烯刺激纤维素和沥青活化为高性能纳米碳的研究基础上，提出石墨烯诱导石油重质油定向构筑石墨烯多孔纳米碳新材料的研制。石墨烯只有表面没有体相，热扩散系数超高，完全具备界面热诱导石油芳香族分子转化为多孔碳的理论基础。本项目将以电化学储能应用为导向，引入石墨烯，定向转化石油沥青为分级多孔纳米碳材料。将调控石墨烯的含量和空洞，原位活化沥青，调控孔结构，提高碳收率，探求氮和硫掺杂碳的原子经济性，构建高性能超级电容器和锂硫电池。拟解决石墨烯界面热诱导沥青活化转化为多孔碳的机理的关键问题。使用原位热重-红外/拉曼-质谱等谱学和TEM原位加热摄像等手段表征活化转化过程，调控产物的微结构、孔分布、导电性和浸润性等参数，适应储能要求，揭示石墨烯和多孔碳的协同作用机制。本项目将为石油重质油提高附加值和储能国家需求提供新思路。

中国石墨资源丰富，石墨烯技术能助其转型升级。石油工业有较多重质油固体废弃物，中国石油等公司期待变废为宝。项目负责人带领团队使用石墨烯诱导石油沥青定向制备出石墨烯多孔纳米碳新材料，并应用于锂硫电池和锂（钠）离子电池负极和电容碳，实验结果证实了项目理论假设。所制三明治结构形态的石墨烯多孔碳新材料的比表面积2900 m2/g，沥青的碳转化率可达70%，应用于锂硫电池和超级电容，性能优异。如正极负载硫量3.0 mg/cm2、电流密度5mA/cm2时，循环1500圈后，比容量400 mAh/g。通过廉价铁盐转化沥青的中的硫为纳米FeS，所得碳材料锂负极性能好，电流密度1000 mA/g，循环700次后比容量可达900 mAh/g。另通过调控铁成分，保留沥青中氮，形成氮掺杂碳，保留硅，形成新的铁硅氮碳基杂化材料，表现出很高的储锂和储钠的性能。如作为锂负极，在1000mA/g下1000循环后，锂比容量900mAh/g；在2000mA/g下1000循环后，钠比容量200mAh/g，倍率性能好。项目研究揭示了石油沥青活化转化为多孔碳材料的石墨烯界面诱导生长机理，阐明了储能应用导向的石墨烯-石油基多孔纳米碳材料的定向构筑调控机制，研究证实了石油沥青中的氮、硅和硫元素保留在最终碳材料产物中的原子经济和其应用于储能材料的可行性。另外，项目研制的石墨烯/碳管分散铁单原子和石墨烯铆钉FeN5催化活性位新结构材料，CO2电还原成CO得法拉第效率95%以上。项目实施中，项目团队分工协作，负责人作为课题组长和博士生导师，负责项目规划、队伍组织、研究生实验指导、数据分析、论文、专利修改。团队成员出国参加国际会议5人次和国内会议40人次。本项目资助发表或接受论文15篇（14篇1区），其中负责人通讯作者13篇，包括Angew Chem、Energy Storage Materials等；成功申请和授权9个发明专利，培养毕业博士生2名和硕士毕业生3名，项目成果超过预期。本项目为碳资源利用提供了科学依据、新思路和技术雏形。