High-temperature electrochemical devices are expected to play an important role in transitioning toward a net-zero world. However, material challenges can be obstacles to reaching technological maturity and thus limit their commercial breakthrough. A thorough characterization of these devices and defined model systems under operational conditions is essential for establishing a mechanistic understanding that can drive urgently needed solutions forward. This work presents a novel, in-house developed two-gas setup for the characterization of high-temperature solid oxide cells, tailored to fit the needs of both model systems and near-application cells.

A key innovation of our system is the custom-designed sample holder, which facilitates rapid sample exchange, supporting high throughput and easy electrical connectivity via up to six separate tip contacts on one side. This feature enables various measurement geometries, including experiments on microelectrodes and the introduction of reference electrodes. The sample holder can be exchanged for samples of several geometries like 5 mm × 5 mm and 10 mm × 10 mm single crystals and round button cells. We show how the holding mechanism was optimized through several iterations for an even pressure distribution on the sample to prevent the cracking of delicate ceramic samples. Further, the gas flow over the sample was optimized for a fast washout of product gases. Several gasket materials were compared regarding tightness, exchangeability, and inertness under high temperatures. The rack is constructed of fully inert materials like alumina, fused silica, and platinum to enable an operation temperature of up to 1000°C. An online coupling of the setup with gas chromatography and mass spectroscopy was used for product gas analysis.

The effectiveness and versatility of our new setup were validated through two distinct applications. The first involved CO production via CO₂ electrolysis on a 10 × 10 mm YSZ single-crystal-based cell with pure GDC (i.e. Ni-free) electrodes. The second application tested anode-supported proton-conducting ceramic cells with a round geometry, exploring different material compositions and sample configurations, including hydrogen pumps, fuel cells, and electrolyzers. Comprehensive electrochemical characterization was performed in both systems, including impedance spectroscopy, current-voltage curve measurements, and gas analytics for Faraday efficiency determination.