Ammonia-fed reversible protonic ceramic fuel cells with Ru-based catalyst

Abstract

The intermediate operating temperatures (~400–600 °C) of reversible protonic ceramic fuel cells (RePCFC) permit the potential use of ammonia as a carbon-neutral high energy density fuel and energy storage medium. Here we show fabrication of anode-supported RePCFC with an ultra-dense (~100%) and thin (4 μm) protonic ceramic electrolyte layer. When coupled to a novel Ru-(BaO)2(CaO)(Al2O3) (Ru-B2CA) reversible ammonia catalyst, maximum fuel-cell power generation reaches 877 mW cm−2 at 650 °C under ammonia fuel. We report relatively stable operation at 600 °C for up to 1250 h under ammonia fuel. In fuel production mode, ammonia rates exceed 1.2 × 10−8 NH3 mol cm−2 s−1at ambient pressure with H2 from electrolysis only, and 2.1 × 10−6 mol NH3 cm−2 s−1 at 12.5 bar with H2 from both electrolysis and simulated recycling gas.

Protonic Ceramic Electrochemical Cells for Synthesizing Sustainable Chemicals and Fuels

“…[4,5,7] However, increasing the current density cannot continuously increase the ammonia production rate. [17] Therefore, it is essential to operate PCECs under an optimal current density to obtain high ammonia yield and energy efficiency. As shown in Figure 7, at a relatively low current density, the negative electrode is covered with sufficient chemisorbed nitrogen that will be readily reduced by hydrogen/proton.…”

“…Numerous lab-scale PCECs have been demonstrated to realize these applications. [5,14,17,23,28] These previous studies have centered on proving the concept of producing chemicals in PCECs. However, the reaction thermodynamics, energy efficiency, potential reaction mechanisms, critical barriers, and potential strategies to overcome the challenges are not discussed in detail.…”

Characterisation of direct ammonia proton conducting tubular ceramic fuel cells for maritime applications

“…49 Zhu et al reported ammonia-fed reversible protonic ceramic fuel cells with a Ru-based catalyst. 52 operating for 1250 h; however, ammonia was cracked in a separate reactor. When the button cell was operated under direct ammonia, the voltage dropped in 15 h. He et al utilised a Pd added electrolyte to produce 0.724 W cm −2 at 650 °C with direct ammonia feed.…”

Understanding the Highly Electrocatalytic Active Mixed Triple Conducting NaxCa3–xCo4O9–δ Oxygen Electrode Materials

“…[2,3] Among them, reversible protonic ceramic cells (RPCCs) based on proton-conducting electrolytes at intermediate temperatures (IT < 700 °C) have various advantages in terms of energy efficiency, durability, and cost, compared to the low-temperature water-splitting unitized reversible fuel cells (URFCs) and high-temperature reversible solid oxide cells (RSOCs). [4][5][6] RPCCs can Despite their high electrocatalytic activity for oxygen electrode reactions, the low phase stability and high thermal expansion of perovskite structured materials have created difficulties in cell fabrication scale-up and long-term operational stability of reversible ceramic cells. Herein, an exceptionally high-performance electrocatalyst is presented based on a misfit-layered structure, Na 0.15 Ca 2.85 Co 4 O 9-δ (NCCO).…”

“…[ 2,3 ] Among them, reversible protonic ceramic cells (RPCCs) based on proton‐conducting electrolytes at intermediate temperatures (IT < 700 °C) have various advantages in terms of energy efficiency, durability, and cost, compared to the low‐temperature water‐splitting unitized reversible fuel cells (URFCs) and high‐temperature reversible solid oxide cells (RSOCs). [ 4–6 ] RPCCs can not only generate high power density, including high CH 4 conversion and carbon coking resistance, but also directly produce high‐purity H 2 without additional equipment and the problem of Ni‐cermet fuel electrode decomposition. [ 7 ]…”