New Materials For Redox Flow Batteries

Lead Research Organisation: University of Cambridge
Department Name: Chemistry

Abstract

Redox flow batteries, with their ability to vary power capacity and energy capacity independently, are a potential way of regulating the power output of renewable energy sources, such as wind and solar. The goal of current research is to increase the energy density of such systems, while providing long operation lifetimes under much milder operating conditions.

This project aims to increase the energy density by considering both new inorganic molecules/ions/clusters using cheap transition metal ions (Fe, Mn, etc.). Tuning of the ionic species towards optimised electrical performance will then be carried out via modification of the ligands present in such species. The species will be characterised initially via electrochemical cycling to ensure the feasibility towards flow batteries; NMR, UV and IR studies will be used to monitor the electrochemical reactions, where possible in situ. Single crystals will be prepared where necessary for structure solution to validate syntheses.

The literature currently presents several organic systems that could also be used in flow battery technology. To this end, development of current systems with a view towards incorporating metal centres may also allow for an increase of energy density and finer tuning of performance metrics. Solubility, however, may limit such an endeavour, as both oxidised and reduced forms of a species needs to be highly soluble to ensure persistence of species in solution.

Publications

10 25 50
publication icon
Jethwa R (2019) Going with the Flow: Novel Quinoidal Electrolytes for Redox Flow Batteries in ECS Meeting Abstracts

publication icon
Jethwa R (2021) Designing for conjugate addition: an amine functionalised quinone anolyte for redox flow batteries in Journal of Materials Chemistry A

publication icon
Lu H (2019) A simple one-step synthetic route to access a range of metal-doped polyoxovanadate clusters. in Dalton transactions (Cambridge, England : 2003)

publication icon
Zhao EW (2020) In situ NMR metrology reveals reaction mechanisms in redox flow batteries. in Nature

publication icon
Zhao EW (2021) Coupled In Situ NMR and EPR Studies Reveal the Electron Transfer Rate and Electrolyte Decomposition in Redox Flow Batteries. in Journal of the American Chemical Society

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R511870/1 01/10/2017 30/09/2023
1944582 Studentship EP/R511870/1 01/10/2017 28/02/2022 Rajesh Jethwa
 
Title Inside-front cover of Journal of Materials Chemistry A, Volume 9, Issue 27 
Description Inside-front cover designed using the experimental and theoretical data from the paper that was published in J. Mater. Chem. A, 2021, 9, 15188. The cyclic voltammograms were used to form the wind-turbine blades, the NMR spectra from the in-situ battery experiment formed the land/sea and the in-situ EPR spectra formed the sky. Models produced using density functional theory calculations can be observed to flow with the wind in the sky. The molecules evolve from left-to-right alongside the electrochemical profiles (on the turbine blades) representing the reaction investigated in the paper. The cover theme is derived from the potential application of redox flow batteries towards accounting for the intermittency of renewable energy sources, such as wind. 
Type Of Art Artwork 
Year Produced 2021 
Impact Increased social media presence of the work contained in the paper (J. Mater. Chem. A, 2021, 9, 15188) with 4 of the 11 tweets surrounding the work referring to the journal cover. 
URL https://doi.org/10.1039/D1TA90147H
 
Description Through a combination of modelling, conventional chemical characterisation and powerful in situ techniques - techniques capable of probing the behaviour of the species of interest during battery operation - novel flow battery electrolytes have been investigated and their battery behaviour probed. For one such molecule, a paper has been published (J. Mater. Chem. A, 2021, 9, 15188) and another publication is in preparation.
Along the course of the PhD, various skills have been developed in order to aid data processing or to understand the limits of the systems being investigated. In terms of battery performance, a combination of physical electrochemical experiments together with more conventional battery cycling allows for an understanding of the stability of the molecules. Electrochemical stability, i.e. the ability of the molecules to be charged and discharged (to take and give up electrons) reversibly, and without breakdown, over many cycles is key for a system such as flow batteries where an installation may see decadal or longer service lifetimes. Utilising this in combination with NMR characterisation of the molecule as the battery is being cycled allows for an understanding of how a molecule might change its behaviour within the more complex environment of a full battery, as compared to the typically more simple, single component systems that are normally used for conventional physical electrochemical experiments. Both of these experimental methods are then reinforced by modelling in order to understand the thermodynamic and kinetic results within the data produced.
Exploitation Route The results incorporated in the thesis and the publications produced alongside the work will allow for better next generation flow battery systems to be developed. By understanding the pitfalls and potential degradation pathways of these redox-active molecules, molecules with a more appropriate potential energy, a greater stability or a greater energy density can be designed. These molecules can then be practically applied to renewable energy installations as a means of smoothing-out supply and demand and accounting for the inherent intermittency that come with wind and solar farms. There is now also another PhD that has started work on this project. They have benefitted from the overlap between their first and my final year.
Sectors Energy,Transport