Durable and High-Performance Thin-Film BHYb-Coated BZCYYb Bilayer Electrolytes for Proton-Conducting Reversible Solid Oxide Cells

Abstract

Proton-conducting reversible solid oxide cells are a promising technology for efficient conversion between electricity and chemical fuels, making them well-suited for the deployment of renewable energies and load leveling. However, state-of-the-art proton conductors are limited by an inherent trade-off between conductivity and stability. The bilayer electrolyte design bypasses this limitation by combining a highly conductive electrolyte backbone (e.g., BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb1711)) with a highly stable protection layer (e.g., BaHf 0.8 Yb 0.2 O 3−δ (BHYb82)). Here, a BHYb82-BZCYYb1711 bilayer electrolyte is developed, which dramatically enhances the chemical stability while maintaining high electrochemical performance. The dense and epitaxial BHYb82 protection layer effectively protects the BZCYYb1711 from degradation in contaminating atmospheres such as high concentrations of steam and CO 2 . When exposed to CO 2 (3% H 2 O), the bilayer cell degrades at a rate of 0.4 to 1.1%/ 1000 h, which is much lower than the unmodified cells at 5.1 to 7.0%. The optimized BHYb82 thin-film coating adds negligible resistance to the BZCYYb1711 electrolyte while providing a greatly enhanced chemical stability. Bilayer-based single cells demonstrated state-of-the-art electrochemical performance, with a high peak power density of 1.22 W cm −2 in the fuel cell mode and −1.86 A cm −2 at 1.3 V in the electrolysis mode at 600 °C, while demonstrating excellent long-term stability.

Electrochemical Synthesis of Ammonia via Nitrogen Reduction and Oxygen Evolution Reactions—A Comprehensive Review on Electrolyte-Supported Cells

“…BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 is an extensively investigated proton-conducting electrolyte, although some researchers have diverged, advocating other compositions as the most studied [22,45,47]. Some researchers have explored doping with elements such as Nd, Sc, In, and Hf, in addition to Y and Yb, to enhance the stability and sinterability of the electrolyte [22,43,44,46,48,54]. Ding et al introduced a novel approach by ball milling, pelletizing, calcining, and crushing the pellets to produce a pure-phase powder on a relatively large scale (up to 4 kg per batch) [55].…”

Comprehensive review and future perspectives: 3D printing technology for all types of solid oxide cells

“…Despite the commendable energy conversion efficiency of SOCs, this high operating temperature can implicitly limit their applicability and pose durability challenges to components like stack modules, promoting side reactions with SOCs [22]. In this regard, intensive research has been focused on achieving decent energy conversion efficiency at lower temperatures through various approaches including material development [23,24], catalyst formation [25,26], and the application of thin electrolytes [27] using deposition equipment. In terms of the process, conventional SOC manufacturing employs traditional ceramic processing techniques, including slurry preparation, tape casting, and sintering [28].…”

Design and Fabrication of Protonic Ceramic Fuel Cells Based on BaZr0.8Y0.2O3−δ |BaZr0.1Ce0.7Y0.1Yb0.1O3−δ Bilayer Electrolyte

“…[34][35][36][37] Nevertheless, a recent study using a BaHf 0.8 Yb 0.2 O 3−δ |BZCYYb bilayer electrolyte cell demonstrated excellent stability without any noticeable increase in the ohmic resistance. 38 While most studies on bilayer electrolytes focus on enhancing chemical stability, only a limited number of studies explored the effect of their transport properties. 35,39 Theoretical investigations showed that a thin layer of lanthanum tungstate (LWO; La 27.8 W 4.2 O 54+δ v 2−δ ) can effectively block hole conduction, leading to reduced leakage currents.…”