Solid-oxide electrolysis cells (SOECs) are power-to-gas (P2G) devices that can convert electricity into fuel gas with a high energy conversion efficiency better than that of other kinds of electrolysis technologies. With external current at high temperature, SOEC can electrolyze steam to produce hydrogen. The objective is to develop a kind of fuel-electrode supported cell (LSC/GDC/YSZ/Ni-YSZ) and national first kW-scale SOEC stacks through a self-assembling technique. Both electrochemical performance will be verified by measuring current-voltage characteristic curves. The electrolysis test showed that the hydrogen production rate of self-developed single cell was 0.31 L/min at 750°C when current reached up to 40 A. After exposure at 750°C for 100 hours, the cell also demonstrated good stability without performance degradation. To build an SOEC stack, cells, metal frame, and metal interconnector were assembled sequentially by ceramic sealing. For stack performance validation, a series of stacks (single-cell stack, 5-cell stack, and 30-cell stack) were used for steam-electrolysis tests. The results showed the hydrogen production rate of 30-cell stack at 750°C could reach 13.70 L/min (at 60 A) and 18.26 L/min (at 80 A), and the efficiency of hydrogen production was estimated as 70.2 % and 80.6 %, respectively. Compared to commercial SOEC products, it indicates that our self-assembled stacks have already obtained superior electrochemical performance.

To meet the national energy policy toward net-zero emissions in 2050, NARI aims to develop high-temperature steam-electrolysis technique through SOEC devices and systems for clean hydrogen production. The subjects include cell fabrication, stack assembly, test platform build-up, and cell/stack performance validation. For SOEC cell fabrication, high catalytic-activity materials can be used as functional layers, and a reliable solid structure can be acquired through a modified sintering method. For SOEC stacks assembling, gas-distribution uniformity can be improved through a self-design interconnect pattern, which is also beneficial to the electrochemical performance. As for SOEC performance validation, the key components, such as evaporator, power supply, and control interface, were integrated to establish a test platform, which can provide gas flow, heat, and power for electrolysis tests in specific reaction conditions. The outcome can be regarded as important knowledge for developing large-scale hydrogen production demonstration in the future.

The research will focus on the work about the mass and energy balance calculation of the balance of plant (BoP) components of SOEC systems, in order to design the domestic first-of-its-kind kW-class high-temperature hydrogen production systems. The electrical and heat efficiency of the SOEC systems will be evaluated through integration tests with SOEC stacks. Furthermore, SOECs can be used as energy storage or hydrogen production unit in an integrated energy system (IES), which can combine heat, electricity, and hydrogen in a more efficient way for industrial application. Therefore, NARI plans to develop SOEC models based on electrochemistry and reaction kinetics theory, in order to simulate the real-time dynamic response and performance variation in steady-state conditions. Herein, SOEC models will be coupled with other physical hardware, such as boiler, gas turbine, etc., by using the cyber-physical simulation approach to investigate the optimization of heat and power dispatch.