面向摩擦纳米发电机能源存储的低自放电高频超级电容器的研究

The development of the Internet of Things has led to the large-scale application of remote micro-power electronic devices, which are hindered by frequent charging or battery replacement. Recently, the development of self-charging power unit integrated with triboelectric nanogenerators and supercapacitors can effectively solve this problem. The excellent high-frequency response of high-frequency supercapacitors corresponds to the frequency of energy output of triboelectric nanogenerators, which promotes the application of self-charging power unit. However, the self-discharge of high-frequency supercapacitors limits the energy utilization efficiency and the capability for long-time power supply. Hence, it is imperative to develop effective strategy to suppress the self-discharge of high-frequency supercapacitors. In this project, polar molecular-dominated heterogeneous electrorheological materials will be introduced into the electrolyte of high-frequency supercapacitors for self-discharge suppression. The viscosity of the electrolyte can be regulated by giant electrorheological effect to reduce self-discharge without affecting the specific capacitance, rate performance, and high frequency response of high-frequency supercapacitors. Combining with theoretical simulation of the pore structure of electrode materials, the mechanism of self-discharge suppression of high frequency supercapacitors will be clarified. By integrating triboelectric nanogenerators with high-frequency supercapacitors of low self-discharge to form self-charging power unit, it will be demonstrated that suppressing the self-discharge of high-frequency supercapacitors was beneficial to improve the energy utilization efficiency of self-charging power unit. This study will not only lead to an effective strategy to improve energy utilization efficiency of self-charging power unit from harvesting environmental energy, prolong continuous power supply for micro-power electronic devices, but also facilitate the development of the Internet of Things.

物联网的发展促进了远程微功率电子器件大规模应用，而频繁充电或电池更换阻碍了此类器件的发展。近来，发展的摩擦纳米发电机和超级电容器集成的自充电能源包可有效解决此问题。且高频超级电容器优异的高频响应契合摩擦纳米发电机输出能量的频率，促进了自充电能源包的应用，但其自放电问题限制了能量利用效率，导致持续电力供应时间短。因此，高频超级电容器自放电问题亟待解决。本项目将极性分子主导的非均相电流变材料引入高频超级电容器电解液中，通过巨电流变效应调控电解液的粘度，在不影响比电容、倍率性能及频率响应的前提下，抑制其自放电。并结合电极材料孔结构理论模拟，阐明减缓高频超级电容器自放电机理，为优化其储能时间提供理论支持。在此基础上，将低自放电高频超级电容器与摩擦纳米发电机集成自充电能源包，提高充电效率。此研究有利于提高自充电能源包收集环境能量的利用效率，延长为微功率电子器件供能时间，促进物联网的发展。

高频超级电容器在微/纳储能系统中发挥着关键作用，然而严重的自放电限制了其在自充电能源包和物联网中的应用。本项目在高频超级电容器电解液中引入钛酸钡@尿素非均相电流变液，利用其巨电流变效应，减缓高频超级电容器的自放电速率。研究了钛酸钡@尿素纳米粒子的形状、尺寸及分散浓度对高频超级电容器比电容、倍率性能、高频性能及自放电的影响，揭示了钛酸钡@尿素纳米粒子减缓高频超级电容器自放电的机理，明确了低自放电高频超级电容器在能源存储中的优势。结果表明，钛酸钡@尿素纳米粒子的加入对高频超级电容器的比电容、倍率性能及高频性能影响较小，但会显著减缓自放电速率，随钛酸钡@尿素纳米粒子尺寸的减小或浓度的增加，自放电速率减慢，球形钛酸钡@尿素纳米粒子的加入，使高频超级电容器电压从2 V下降到1.0 V的时间延长了3.5倍。通过自放电曲线模拟对比，表明高频超级电容器的自放电机理是由漏电阻和法拉第反应机理组成，由于碳酸钡@尿素纳米粒子在电场的作用下，产生巨电流变效应，极大地增加电解液的粘度，因此，钛酸钡@尿素纳米粒子的加入减缓了由扩散控制的法拉第反应引起的自放电速率。最后，将高频超级电容器与旋转式摩擦纳米发电机集成自充电能源包，添加钛酸钡@尿素纳米粒子的高频超级电容器的充电时间缩短了5倍，反映了低自放电高频超级电容器集成的自充电能源包有更高的能量利用效率。此项目的研究成果为低自放电高频超级电容器的发展提供了研究基础，有利于推动物联网及传感网络的发展。