NiO/8YSZ Electrode Support Pellet (Disk & Sheet) for SOFC/SOEC Test, CSOFECNiO8YSZESP

In the study of Solid Oxide Fuel Cells (SOFC) and Electrolysis Cells (SOEC), a NiO/8YSZ pellet is the precursor for the most common "anode-supported" cell configuration. While 8YSZ is an electrolyte material, a pellet containing NiO is technically an electrode support, not the electrolyte itself. In this configuration, a thick, porous NiO/8YSZ disk (typically 0.5--1.5 mm) provides the mechanical strength for the entire cell, while a very thin, dense layer of pure 8YSZ (typically 5-20 um) is applied on top to serve as the electrolyte.

The NiO/8YSZ pellet is a "pre-functional" material. It only becomes an active electrode after a reduction process: (1) As-Sintered State: The pellet consists of Green Nickel Oxide (NiO) and White 8YSZ. In this state, it is a ceramic insulator. (2) Reduction Step: During the initial "start-up" of the test (at 600-800 °C under H2), the NiO is reduced to metallic Nickel (Ni). (3) Cermet Result: This creates a Ni-YSZ cermet (ceramic-metal composite). The Ni provides electronic conductivity and catalytic activity, while the 8YSZ provides ionic conductivity and mechanical stability.

References:

1. A. Hauch, et al., Ni/YSZ electrodes structures optimized for increased electrolysis performance and durability, Solid State Ionics, 2016, 293, 27-36. 
2. Hari Prasad Dasari, Electrochemical characterization of Ni–yttria stabilized zirconia electrode for hydrogen production in solid oxide electrolysis cells, J. Power Sources, 2013, 240, 721-728.