Advancements in copper flow battery systems: Performance, modelling, and control strategies

Abstract

Transition to an economy based on renewable energy demands scalable, efficient, and long-duration energy storage solutions to become a reality, with flow batteries having emerged as a leading technology to fulfil this need. This work focuses on the development and optimization of the all-copper redox flow battery and addresses critical performance and characterization challenges that are currently limiting commercial viability. Through systematic engineering and development, the systems current and voltage efficiencies have been greatly improved through stable copper deposition and improved material selection. Further advancements were made through the use of ion exchange membranes and the modification of porous substrates with ion selective polymers to achieve low rates of self-discharge together with high current efficiency over hundreds of hours of continuous operation. In addition to this characterization, this work developed novel methodologies to deepen our understanding of the all-copper flow battery, including the implementation of streaming potential measurements, and the development of a scanning electrochemical microscopy technique to gain temporal and spatial insights into membrane permeability and species crossover. These developments were complemented by the creation of a first principles control-oriented electrochemical model which was calibrated using a genetic algorithm technique, enabling accurate estimations of the systems state, degradation, and state of health over extended operation. Through targeted material development and dynamic modelling the efficiency, durability, and practicality of the all-copper flow battery was improved. Furthermore, the work provides guidance for the future scaling-up of the all-copper flow battery and informs strategies for continued development, thereby supporting the broader goal of the adoption of sustainable energy storage.