Tuning the Frequency Response of Fractional-Order Microsupercapacitors

双层电电容器（EDLC）是电化学电容器的一个子集，它可以在直流和相对远离直流的频率下存储和传递电能，其有效电容介于铝电解电容器和二次电池之间。它们主要用于传统的储能应用中作为二次电源，如微处理器和太阳能电池。它们也被证明是振荡器和滤波器电路、分数阶控制器和分数阶谐振器中的高效能量器件。然而，由于其电极的性质和多孔结构以及电极/电解质相的界面电化学，其性能指标的许多基本方面仍然没有得到很好的理解，合理的设计实际上是不存在的。特别是，edlc在远离直流电且阻抗角在-90°到0°之间时表现出耗散、阻容性行为。在本项目中，基于结构化2D和3D电极阵列的小型化edlc将被设计和制造，目的是理解和控制其非理想的分数阶行为。我们将开发和研究掺杂电解质的影响，以便在存在物理障碍的情况下调整电场诱导的离子输运。期望的结果是一个通用的程序和设计规则，用于微调和控制edlc的阻抗相移及其能量-功率性能。使用平均场Poisson-Nernst-Plank模型进行建模和仿真，以便对器件的频率响应提供基本的理解。使用分数阶数学工具和等效电路模型的系统级建模也将与基于rc的电路相结合。将验证edlc的可控分数阶行为，并演示其频域应用。这个项目将有助于佛罗里达国际大学的研究、教育和多样性目标。该项目的目标是通过实验和建模方法解决在频域指标和分阶电容器性能方面缺乏知识的问题。我们的目标是研究以下内容：(1)电极-电解质界面规格和电解质参数，这些参数能够在扩展的频率带宽上调谐EDLC的电气特性；(2) EDLC的支撑电解质中发生的电动力学效应，以及它们如何影响器件的频域指标；(3)利用3d电路互连和有限元方法进行建模，了解整体电气特性；(4) edlc的频率响应及其在（频域）滤波和（时域）存储中的应用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Electric double-layer capacitors (EDLC) are a subset of electrochemical capacitors that can store and deliver electrical energy at dc and relatively far-from-dc frequencies with effective capacitance between that of aluminum electrolytic capacitors and secondary batteries. They are mostly employed in conventional energy storage applications as secondary power source, such as microprocessors and solar batteries. They have also been demonstrated as efficient energy devices in oscillators and filters circuits, fractional-order controllers, and fractional-order resonators. However, because of the nature and porous structure of their electrodes and the interfacial electrochemistry of their electrodes/electrolyte phase, many fundamental aspects of their performance metrics are still not well understood, and rational design is practically nonexistent. In particular, EDLCs exhibit a dissipative, resistive-capacitive behavior when operating away from dc with an impedance angle anywhere between -90 and 0 deg. In this project, miniaturized EDLCs based on structured 2D and 3D electrode arrays will be designed and fabricated with the objective of understanding and controlling their non-ideal, fractional-order behavior. We will develop and study the effect of doped electrolytes in order to tune the electric-field-induced ionic transport in the presence of physical obstacles. The expected outcome is a general procedure and design rules to apply in order to fine-tune and control the impedance phase shift of EDLCs and their energy-power performance. Modeling and simulation using mean-field Poisson-Nernst-Plank model will be carried out in order to provide a fundamental understanding of the frequency response of the devices. System-level modeling using fractional-order mathematical tools and equivalent circuit models will also be developed in connection with RC-based circuitry. The controllable fractional-order behavior of the EDLCs will be verified and their frequency-domain application will be demonstrated. This project will contribute to the research, education, and diversity goals of Florida International University.The objectives of this project are to tackle the lack of knowledge on the frequency-domain metrics and performance of factional-order capacitors using both experimental and modeling approaches. We aim to investigate the following: (1) electrode-electrolyte interface specifications and electrolyte parameters that enable the tuning of the electrical characteristics of an EDLC over an extended frequency bandwidth; (2) the electro-kinetic effects taking place in the supporting electrolyte of an EDLC, and how they affect the frequency-domain metrics of the device; (3) modeling using 3D-circuit interconnects and finite-element methods to understand the overall electric characteristics; and (4) the frequency response of the EDLCs and their application in (frequency-domain) filtering and (time-domain) memory applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.