APPLICATION OF TECHNOLOGY:
- Energy storage devices for transportation and grid
Nearly all battery technologies today rely on carbon black or conductive carbon mesh as 3-D current collectors. Replacing these ubiquitous conductive carbons with well-defined molecular materials and their self-assembled networks is an entirely new way of achieving electronic conductivity during charge and discharge of an energy storage material.
Berkeley Lab and MIT researchers led by Brett Helms have developed the first soluble redox mediators for metal-sulfur batteries. These redox mediators are pi-conjugated organic molecules known as polycyclic aromatic hydrocarbons (PAHs). When in place in the electrochemical cells, these redox mediators increase the efficiency of interfacial charge transfer between sulfur and embedded carbon electrodes, and facilitate short-range electronic charge transport throughout the sulfur electrode.
Several of the redox mediators discovered assemble into complex 3D networks in electrolyte, and others do so as polysulfides are electrochemically generated during cell operation. The resulting supramolecular networks are capable of three-dimensional electric conductivity, and are shown to have self-healing character. These unique attributes result in higher capacity and higher energy density, particularly for flowable sulfur electrodes used in redox flow batteries.
Redox flow batteries offer the opportunity to locally store energy produced by renewable yet intermittent energy sources such as the sun and wind. Regardless of the energy storage media used, electronic charge must be efficiently transferred between the storage materials and the current collector when the solutions (or suspensions / dispersions as applicable) of redox active molecules are flowing through an electrochemical cell.
Current metal-sulfur battery technology relies solely on conductive carbons, heterogeneous materials that lack tunability and can become passivated with insulating species during cell operation. PAHs alleviate these problems and are thus complementary to conductive carbons. Their pairing permits cognizant tuning of interfacial charge transport to maximize power, minimize charge time, and improve sulfur utilization.
- Tunable electrophysiochemical characteristics
- Improves interfacial electron transfer and short-range electronic charge transport
DEVELOPMENT STAGE: Proven Principle.
STATUS: Published U. S. Patent Application #15/502,479 (publication #US-2017-0222226-A1). Available for licensing or collaborative research.
“Three-Dimensional Growth of Li2S in Lithium–Sulfur Batteries Promoted by a Redox Mediator,”ACS Nano Lett. 2016, 16, 1, 549–554
SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:
Nanocrystal Native Ligand Stripping, IB-3124