Ti3+自掺杂TiO2基锂离子混合电容器及储能性能提升研究

Black Ti3+ self-doped TiO2 with abundant oxygen defect/Ti3+ ions are attracting wide attention in various areas such as catalysis, sensor, field emission, microwave absorbing, energy storage, and so on. Up to now, various methods, including hydrogen thermal treatment, hydrogen plasma, chemical reduction and electrochemical ways, have been developed to fabricate black defect-engineered TiO2. Among which, electrochemical methods are usually performed in mild conditions, which are more convenient and controllable. In this project, we will design an AC electrochemical method for synthesis of black Ti3+ self-doped TiO2 hybrid capacitor anode nanocrystals with high electrical conductivity, high capacity, outstanding rate capability and excellent cycle performance, and mainly focus on the intrinsic link between the oxygen defect/Ti3+ ions and the lithium storage mechanism. Meanwhile, we will develop an aldol reaction assisted by electrochemical anodic oxidation for the fabrication of nitrogen and sulfur co-doped porous activated carbon electrode materials. The mechanism for materials synthesis and competition or collaborative effect of surface/interface factors (such as N/S doping ) on the properties of supercapacitor will also be carried out in detail. On this foundation, an advanced lithium ion hybrid capacitor with high voltage, large energy/power density and suitable electrolyte solution can be achieved utilizing the as-designed Ti3+ self-doped TiO2 anode and N, S co-doped porous activated carbon cathode.

黑色Ti3+自掺杂TiO2具有氧缺陷和Ti3+离子，在催化、传感、场发射、微波吸收、燃料电池、锂离子电池及超级电容器等领域具有诱人的应用景。然而，当前方法制备Ti3+自掺杂TiO2成本偏高、步骤较复杂。本项目拟开发一步交流电电化学法合成黑色Ti3+自掺杂TiO2纳晶，并阐明氧缺陷和Ti3+离子与储锂性能之间的内在联系，制备出高容量、倍率性能和循环性能优异的混合电容阳极材料；同时开发电化学阳极辅助羟醛缩合反应合成氮、硫掺杂碳材料，探究制备机理，解析N、S掺杂等表/界面因素对多孔炭电容特性的竞争及协同影响效果，构建高容量双电层多孔炭阴极；在此基础上，匹配具有良好浸润性与高离子电导率的电解质溶液，优化电容器结构，构建工作电压高、能量/功率密度大的锂离子混合电容器。

黑色Ti3+自掺杂TiO2具有氧缺陷和Ti3+离子，在催化、传感、场发射、微波吸收、燃料电池、锂离子电池及超级电容器等领域具有诱人的应用景。然而，当前方法制备Ti3+自掺杂TiO2成本偏高、步骤较复杂。本项目探索了不同电解液、不同的交流电下钛金属的剥离行为，发现金属钛在中性电解液中在方波、三角波等交流电下皆可被剥离成黑色Ti3+自掺杂TiO2纳米颗粒，进一步地将其在高温500-600 C下惰性气氛中热处理可获得结晶完好的Ti3+自掺杂TiO2纳米晶。该材料应用于锂离子混合电容器阳极材料在0.5 C下比容量达到271 mAh/g，超高倍率20 C下依然有159 mAh/g，且具有较好的循环性能：200次充放电循环后容量保持率达98.5%。以丙醇为原材料采用电化学辅助羟醛缩合反应辅以高温碱活化合成了氮掺杂多孔炭，探索了掺杂对材料电导率、比表面积及电化学性能的影响；最终优选了电解液、正负极材料配比，获得了能量密度达56 Wh/kg（200 W/kg下）循环寿命长的（1000次循环之后的容量保持率为97.8%）的锂离子混合电容器。此外，本项目在研究钛基混合锂离子电容的同时，也开展了钛基阳极材料及钠离子混合电容器的研究，以电化学剥离合成的TiO2、活性炭分别为阳、阴极材料，优化了粘结剂、电解液，极大地提升了TiO2的首次效率、比容量、倍率及循环性能，研究了储钠机制、SEI成分、赝电容贡献等对电化学性能的影响，最终获得了能量密度及循环性能与上述锂离子混合电容器相当的钠离子混合电容器。此外，还扩展了本项目开发的交流电电化学剥离法在Mn3O4、birnessite -MnO2、Co(OH)2、WO3、MoO3等低维材料制备中的应用；进一步地开发了纯阴极电化学剥离法合成了铋烯、锑烯等新兴二维材料，并探究了它们在新型储能器件领域如钠离子电池、锌离子电池等领域中的应用。