Thin-Film, Metal-Supported High-Performance and Durable Proton-Solid Oxide Electrolyzer Cell

Recipient United Technologies Research Center (PI: Tianli Zhu)

Water Splitting Technology HTE

Status Awarded

Abstract High temperature electrolysis can be a highly efficient and cost competitive process for H2 generation when coupled with nuclear power or renewable sources such as wind or solar. The major challenge is the high degradation rate (1-4%/1000 h) of conventional oxygen-ion conducting solid oxide electrolyzers due to material and interface degradation at high temperatures (typically 800-1100 ºC). United Technologies Research Center (UTRC) proposes to demonstrate a thin- film, high efficiency and durable metal-supported Solid Oxide Electrolysis Cell (SOEC) based on proton-conducting electrolyte at targeted operating temperatures of 550-

650ºC. The proposed project leverages material and fabrication processes developed under ARPA-E’s REBELS project, with further advancements through modeling, material discovery and testing capabilities at UTRC and the National Laboratories through the HydroGEN Consortium. The proposed project seeks to demonstrate a high temperature SOEC cell that should meet all of DOE’s efficiency and durability targets.

SOEC system based on p-conducting electrolytes provides several major advantages over conventional SOEC system based on oxygen ion-conducting electrolytes: 1) proton conducting oxides offer tremendous potential for the realization of SOEC stacks at temperatures of 500-700

C, reducing metallic interconnect corrosion rates and eliminate the emission of cell poisoning volatile compounds; 2) it produces pure and dry H2 at the hydrogen electrode thus eliminating the need of H2 separation downstream;; and 3) it can be switched to fuel cell mode by applying potential values higher than the open circuit voltage, making the concept of a reversible SOFC more feasible.

The project should enable a water splitting system that can potentially meet all of the DOE performance targets, i.e., achieving 1A/cm2 at 1.4 V, durability for targeted 40,000 h life and H2 production cost of $2/kg H2. The team shall leverage recently demonstrated high performance electrolyte and electrode materials, and utilize molecular modeling and high-throughput methodology to enable additional material improvements. The proposed thin-film deposition process would further reduce the cell resistance through reduced electrolyte thickness, as well an improved electrolyte/electrode interface. This will be combined with the thin-film deposition by low-cost cell fabrication technologies which eliminate high T sintering, and a metal-cell design, which are both currently being developed as part of UTRC’s ARPA-E project, to provide high performance and low-cost cells.

The team plans to utilize the word-class capabilities of the HydroGEN Consortium. The collaborations potential include: new material discovery with INL through modeling and high-throughput combinatorial experiment thin film; durability testing under control environment at INL; alternative cell fabrication on metal support with LBNL; metal alloy durability evaluation and mitigation with LBNL; and metal cell design optimization through cell level modeling with NREL.

The funding shall enable significant acceleration of the proposed technology, better understanding of p-conducting SOECs and metal-supported cells, and extensive collaboration with HydroGEN Consortium. It shall also accelerate the commercialization of high-temperature electrolysis, as well as advance reversible-SOFC technology for renewable-energy applications.