Tuning the Frequency Response of Fractional-Order Microsupercapacitors

双电层电容器(EDLC)是电化学电容器的一个子集，它以铝电解电容器和二次电池之间的有效电容，在直流电和相对远离直流的频率下存储和传输电能。它们大多用于传统的储能应用，作为二次电源，如微处理器和太阳能电池。它们还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的有效能量器件。然而，由于它们电极的性质和多孔结构，以及它们电极/电解液相的界面电化学，它们的许多基本性能指标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在远离直流工作时表现出耗散、阻容行为，阻抗角在-90°和0°之间。在这个项目中，我们将设计和制造基于2D和3D结构电极阵列的小型化EDLC，目的是了解和控制它们的非理想、分数阶行为。我们将开发和研究掺杂电解质的效应，以便在存在物理障碍的情况下调整电场诱导的离子传输。预期的结果是应用一个通用的程序和设计规则来微调和控制EDLC的阻抗相移及其能量-功率性能。将使用平均场Poisson-Nernst-Plank模型进行建模和仿真，以提供对器件频率响应的基本了解。还将结合基于RC的电路开发使用分数阶数学工具和等效电路模型的系统级建模。将验证EDLC的可控分数阶行为，并演示其在频域中的应用。该项目将为佛罗里达国际大学的研究、教育和多样性目标做出贡献。该项目的目标是通过实验和建模方法，解决对派序电容器的频域指标和性能缺乏了解的问题。我们的目标是研究以下内容：(1)电极-电解液界面规范和电解液参数，使EDLC的电学特性能够在扩展的频带内调谐；(2)EDLC的支持电解液中发生的电动效应，以及它们如何影响器件的频域指标；(3)使用3D电路互连和有限元方法进行建模以了解整体电学特性；以及(4)EDLC的频率响应及其在(频域)滤波和(时间域)存储器应用中的应用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.