Transport through Carbon electrodes and New Catalysts for an Organic-Air Hybrid Redox Flow Battery

将不同的能源利用技术结合起来，建立一个可再生能源网络，对于向联网者提供安全可靠的电力至关重要。迄今为止，用于利用可再生能源的最有前途和最有效的技术是太阳能光伏阵列和风力发电场。这些能源的间歇性是一个问题，但可以通过使用大规模储能设备来管理。氧化还原液流电池（RFBs）是一种相对新兴的技术，它可以以较低的价格向电网提供较长时间的能量存储。获得极化和阻抗谱数据，并用于确定作为电解质粘度和流速和电极的热处理的函数的系统的性能。收集压缩电极的非原位X射线断层扫描数据，以突出微观结构参数如何有助于解释电池的整体性能。虽然上述方法有助于我们了解RFB的阳极组件（有机侧）中发生的过程，但阴极（空气侧）需要更多的工作。在开发“空气电极”时，必须首先开发允许氧还原和析氧反应（ORR/ORR）发生的有效双功能电催化剂，并随后将其附加到碳（/其它导电材料）载体上。这项工作的第二部分旨在开发一种电催化剂，最终将用于这种有机-空气混合RFB的阴极。使用ORR和OER的简单LSV / CV扫描作为指标，优化了催化剂的合成路线，并且催化剂显示出在不同pH下的耐受性，而不像许多电催化剂仅在特定pH下有效。碳基质、ZIF-67的尺寸和整体形态影响性能。合成路线确保较低负载量的铱被金属转移到催化剂中，因此质量活性远高于商业OER材料。对于性能最好的材料，E为724 mV，这与最先进的双功能催化剂相比具有竞争力。

Incorporation of different energy-harnessing technologies creating a renewable energy network is important for providing safe and reliable power to those connected. To date, the most promising and effective technologies used to harness renewable energy sources are solar photovoltaic arrays (PV) and wind farms. The intermittent nature of these sources of energy is a problem but can be managed with the use of large-scale energy storage devices. Redox Flow Batteries (RFBs) are a relatively nascent technology which would allow longer term energy storage to the grid for a lower price.Symmetric single-electrolyte flow cell testing is used to compare carbon paper / cloth electrodes with different microstructural properties. Polarisation and impedance spectroscopy data are obtained and used to determine the performance of the system as a function of electrolyte viscosity and flow rate and heat treatments of electrodes. Ex-situ X-ray tomographic data of compressed electrodes is gathered to highlight how microstructural parameters might help to explain overall performance of the cell.This project aims to develop a full organic air RFB system. While the above methods help us to understand the processes happening in the anode component (organic side) of the RFB, the cathode (air side) requires more work. In developing an 'air electrode,' an effective bifunctional electrocatalyst that allows both the oxygen reduction and evolution reactions (ORR/ORR) to happen must first be developed and subsequently appended to a carbon (/other conductive material) support.Creation of an air-breathing electrode would dramatically increase the power density and reduce the associated costs for RFB operation. The second part of this work seeks to develop an electrocatalyst that will ultimately be used in the cathode of this organic-air hybrid RFB. Using simple LSV / CV scans for ORR and OER as indicators, the synthesis route of the catalyst is optimised, and the catalyst is shown to be resistant at different pHs, unlike many electrocatalysts that are only effective at specific pHs. The carbon substrate, ZIF-67's size and overall morphology influences the performance. The synthesis route ensures a lower loading of iridium is transmetallated into the catalyst and therefore the mass activities are much higher than with commercial OER materials. For the best performing material, E is 724 mV, which is competitive with state-of-the-art bifunctional catalysts.