There is growing consensus that major steps must be taken immediately to mitigate global warming. A key step is the rapid expansion in the use of renewable energy sources. However, since much of the new renewables will be wind and solar, which are intermittent electrical energy sources, it will be essential to both store electricity and convert it to chemical fuels. This proposal focuses on a novel energy storage/conversion technology – the reversible solid oxide cell (ReSOC). Although similar to the solid oxide fuel cell, a ReSOC is operated in reverse (electrolysis mode) to produce renewable fuels directly or to enhance biomass production, or alternating between electrolysis and fuel cell modes to accomplish electricity storage. Recent studies show that ReSOCs can yield very high conversion efficiencies at reasonable cost and with extremely high energy storage capacity. However, these different modes of operation, along with a different range of device operating conditions, put new demands on materials and device durability. Long term stability is especially important because the devices must operate over long times (> 40,000 h and thousands of storage cycles) to be economically viable. The proposed project aims to study the structure, ion and electron transport properties, stability, and electrochemical characteristics of electrode materials employed in ReSOCs. Based on the requirement to operate at relatively low temperature ( 650 oC), ReSOC electrodes are typically complex oxides with fast oxygen ion transport kinetics, with performance enhanced by using a high-surface-area nano-scale structure. One main aim of this project is to understand how materials properties and structure determine electrochemical characteristics; this will be done using electrochemical models with inputs including 3D tomographic microstructure data and measured materials properties. The other main aim is to understand and model degradation mechanisms related to cation transport, such as particle coarsening and surface segregation. Electrode overpotentials and currents present during device operation can also affect degradation, both via new degradation effects such as electrode delamination, and by affecting cation transport. Note that seemingly small electrode overpotentials yield “extreme” effective oxygen partial pressures, >103 atm at the oxygen electrode and &lt;10-28 atm at the fuel electrode, that can cause serious degradation.
|Effective start/end date||12/1/16 → 11/30/22|
- Department of Energy (DE-SC0016965-0003)