抗振动疲劳多孔碳薄膜电极的燃烧制备及电化学表征与分析研究

A carbon aerogel, composed of carbon nanotube and grapheme, possesses excellent electrochemical and mechanical performances. It has potential to be applied in elastic electrochemical device as functional thin-film of electrode. However, the carbon aerogel is high-cost, and it is difficult to maintain stable electrochemical performances when the electrode is under sustained vibrations. These shortages restrict its application. In this project, the dye-sensitized solar cell serves as researched electrochemical device. In order to meet the requirements for application, a combustion synthesis method will be employed to develop a low-cost porous carbon thin-film counter electrode, which is composed of carbon nanotube, graphene and conductive binder, and is based on an elastic and conductive substrate. A time-domain and real-time fatigue test system with bidirectional bending function will be constructed, and the fatigue failure and its evolution for carbon electrode will be directly characterized by electrochemical parameters. The finite element mechanical model, electrochemical equivalent circuit model and carrier transport model will be established, based on the thin-film, micro- and nano-mechanics experiments. The stability study for key electrochemical parameters will be carried out, which will be used to investigate the effect of preparation and macro- and mirco-structure on fatigue performance. The investigation especially focuses on the mechanism of residual stress and interface infiltration on fatigue performance. A carbon electrode with low-cost, high electrochemical performance and long fatigue life will be developed. The interaction mechanism between electrochemical stability and vibratory fatigue performances will be clarified. These will lay a good foundation for the study of complex carbonaceous electrochemical device with anti-vibration fatigue property.

碳纳米管-石墨烯复合而成的碳气凝胶具有优异的电化学与力学性能，有潜力作为电极的功能薄膜材料，应用于弹性电化学器件，然而，其成本较高，且在持续振动下电化学性能难以保持稳定，不利于实际应用。本项目以染料敏化太阳能电池为研究对象，面向实际应用，采用燃烧法研制低成本的、基于弹性导电衬底的、碳纳米管-石墨烯-粘合剂复合的多孔碳薄膜对电极；建立时域/实时双向弯曲疲劳测试系统，采用电化学参数直接表征碳电极的疲劳失效及演变；基于薄膜与微纳米力学等实验，建立有限元力学模型、电化学等效电路与载流子输运模型，通过分析关键电化学参数的稳定性，从而研究制备工艺、材料宏观/微观结构对疲劳性能的影响，着重研究残余应力和界面浸润对疲劳失效的影响机理；制得低成本、高电化学性能且长疲劳寿命的碳电极，揭示碳电极的电化学稳定性与振动疲劳性能的关联机理，为复杂的抗振动疲劳弹性碳基电化学器件的研究打下基础。

基于掺杂石墨烯的碳气凝胶具有优异的电化学与力学性能，有潜力作为电极功能材料，应用于弹性电化学器件，然而，其成本较高，且在持续振动下电化学性能难以稳定，不利于实际应用。本项目选用电化学超级电容器为研究对象，面向实际应用，1）采用燃烧法及水热-自然干燥法研制了低成本的、基于弹性导电衬底、石墨烯基材的复合多孔碳电极，如Mn3O4嵌入的中空碳纳米球、CoMn2O4-石墨烯复合多孔薄膜、基于氮、硼、硫的二元/三元掺杂石墨烯气凝胶等，其质量比电容最高为1783 F g-1；2）基于电容保持率-时间、输出电流/电压-时间等测试方法建立了时域双向弯曲及压缩疲劳测试系统；基于恒流充放电测试方法，建立了实时压缩(振动)疲劳测试系统，研究发现电化学参量(电容值、等效电阻、电阻/输出电流/面电容变化率等)的变化能够直观表征碳电极的疲劳失效及演变规律；3）基于材料、结构及器件宏观与微观特性，建立电化学等效电路与载流子输运模型，通过分析关键电化学参数，研究制备工艺、材料宏观/微观结构对疲劳性能的影响，研究发现残余应力对机械能-电能转化发挥关键作用，其不仅在单应力加载/卸载过程中保持结构内部的力学平衡，而且能够随时间缓慢释放外加应力的电化学效果；由于器件内部电解质/电极材料的界面吸附/解吸附效应，应力在内电场作用下会激发极化电荷进而贡献电化学性能；4）制得低成本、高电化学性能且长疲劳寿命的碳电极，其作为超级电容器电极时，其电容值为52±5 mF，当样品做双向弯曲循环振动(振动频率接近系统固有频率，振幅5-6mm，循环次数36000)时，电极的电容衰减为21.7%；5）研究了机械能-电化学能的转化机理，且探索开发了弹-电化学应力传感器，其可作为今后长期的研究方向。在本项目的资助下，本人以第一作者或通讯作者在SCI一区刊物上发表高质量研究论文5篇；申请国家发明专利7项；参加国内国际会议2次；培养硕士研究生3名。