Design and Modelling of Organic/Hydrogen Redox Flow Battery Systems

Flow batteries are an attractive emerging option to provide energy storage in support of grid stability as increasing levels of renewable generation are added into the energy system. They are particularly well suited for applications where longer-term energy solutions are needed, typically in the range of 4-24 hours. Current flow battery technologies are based around the use of vanadium electrolytes, which remain costly. This project will explore new organic flow battery chemistries which offer the prospect of lower energy storage costs.
This project aligns fully with the EPSRC Energy Storage research area and with other UK initiatives such as the Faraday Battery Challenge, and policies such as the Clean Growth Strategy and Road to Zero. It also links to other key EPSRC research areas such as Energy Networks. Furthermore, this project complements the ongoing Shell-ICL project on Organic redox couple-Hydrogen RFBs.

Organic redox flow batteries hold significant promise for low cost high capacity redox flow batteries, figure 1[1]-[7]. Recently the Kucernak group at Imperial has started examining the use of Organic redox couple-Hydrogen RFBs which have theoretical capacities of >20 Wh/L (more than twice that of any other recent organic RFB system) and has achieved capacities significantly better than those achieved in other RFB systems[8]. However that work has highlighted some further issues associated with organic electrolytes, specifically associated with degradation of the electrolyte and specific issues associated with the operation of these systems.
Hence, this project will combine experimentation with modelling and simulation to look at the dynamic response of a flow battery based around organic redox couple- hydrogen systems. Suitable organic couples will be tested in a hydrogen-organic redox flow battery and the performance evaluated. The student will examine organic electrolyte permeation through commercially available membrane materials and test selected membranes developed in Dr Qilei Songs laboratory. Work will be performed to look at the longer term operation of these systems and establish degradation mechanisms and degradation rates of the materials involved. The researcher will collaborate with the modelling PhD student to provide input data needed to refine the model of an organic-hydrogen RFB. The student will perform experimental work to provide input data for the model, and for model verification purposes at the cell level. The student will also work with Shell to enable the techno-economics of the technology to be considered.
The key targets for the organic electrolytes are:

(a) Establish electrolyte permeability through appropriate membrane materials (using Nafion as a reference). Test other appropriate materials (e.g. from Dr Qilei Songs laboratory)
(b) Optimise electrode structure to provide fast electrokinetics with organic electrolytes by incorporation of nitrogen functionality and single atom metal catalysts
(c) Test performance of materials in Hydrogen-organic redox flow battery as function of number of cycles
(d) Collaborate with modelling PhD to produce model of organic RFB system using parameters determined from testing cell
(e) Develop approaches to sample electrolyte and establish degradation products using nmr and ion chromatography
(f) Develop mitigation strategies to allow high cycle life (>200 cycles at 100% dod) in organic electrolytes using the information determined from (d)
(g) Achieve organic electrolyte achieved Energy capacity > 20 Wh/L with >200 cycles
We aim to generate fundamental understanding of the operation of hydrogen-organic electrolytes in redox flow batteries including modelling of the system from a technical and technoeconomic viewpoint.