(350e) Novel Nanoscale Hybrid Electrolytes with Unique Tunability for Sustainable Energy Storage

The recent growth in the worldwide installation of renewable energy has allowed the first steps towards decarbonization of power sector. However, further penetration of renewable energy into the grid is challenged due to the limitations of storage of intermittent renewable electricity. Thus, vast research efforts are on-going to develop electrochemical energy storage systems such as batteries and dense energy carriers. Electrolyte design and selection plays a key role in the development of these electrochemical energy systems, mediating transport and solubility of the reactive species to ultimately deliver high energy, current and power density systems.

A novel class of nanoparticle organic hybrid materials (NOHMs) has been developed that can serve as breakthrough electrolytes with concentrations of electrochemically active species that are not achievable in other conventional solvents. NOHMs based mixtures have shown higher conductivity compared to pure polymer and due to the tunability of the constituent polymers, NOHMs can be tailored as versatile electrolyte media for redox flow batteries and other electrochemical systems, such as electrochemical conversion of CO₂ to dense energy carriers, NOHMs-based electrolytes have shown high CO₂ solubility, as well as the ability to selectively complex redox active species such as copper and zinc, increasing their effective concentration in solution and enabling improvements in energy densities.

NOHMs-based electrolytes have been found to have highly tunable physicochemical and electrochemical properties. The electrochemical behavior of NOHMs-complexed copper (II) species has been explored, indicating changes of the overall conversion mechanism through stabilization of the copper (I) state. This electrochemical behavior can be tailored by varying the solution pH, by which the degree of copper (II) chelation can be controlled. Tailoring transport properties is also of particular importance in NOHMs-based electrolytes mixtures, as they are challenged by inherently high viscosities, impacting charge transport critical in electrochemical performance. These physicochemical properties can be tuned by controlling the intermolecular interactions between the polymeric canopy and the surrounding fluid. In particular, NOHMs have been found to be highly responsive to ionic stimuli, with the addition of even low salt concentrations inducing large reductions in the viscosity of NOHMs-based electrolyte mixtures. Alterations in the degree of polymer swelling and the conformational structure of the NOHMs polymer canopy with ionicity have been probed via Dynamic Light Scattering and Diffusion NMR to explain measured bulk physicochemical properties.

Overall, NOHMs have been found to be electrolyte materials enabling high concentrations of electrochemically active species and with highly tunable transport properties, making them versatile electrolytes for a variety of electrochemical energy storage systems.