Single-phase La0.8Sr0.2Co1-Mn O3- electrocatalyst as a triple H+/O2-/e- conductor enabling high-performance intermediate-temperature water electrolysis
Ning Wang, Chunmei Tang, Lei Du, Zhao‐Qing Liu, Weiyan Li, Zhongqian Song, Yoshitaka Aoki, Siyu Ye
Abstract
Hydrogen, especially the “green hydrogen” based on water electrolysis, is of great importance to build a sustainable society due to its high-energy-density, zero-carbon-emission features, and wide-range applications. Today's water electrolysis is usually carried out in either low-temperature (<100 °C), e.g., alkaline electrolyzer, or high-temperature (>700 °C) applications, e.g., solid oxide electrolyzer. However, the low-temperature devices usually suffer from high applied voltages (usually >1.5 V @0.01 A cm−2) and high cost; meanwhile, the high-temperature ones have an unsatisfied lifetime partially due to the incompatibility among components. Reasonably, an intermediate-temperature device, namely, proton ceramic cell (PCC), has been recently proposed. The widely-used air electrode for PCC is based on double O2-/e- conductor or composited O2-/e-−H+ conductor, limiting the accessible reaction region. Herein, we designed a single-phase La0.8Sr0.2Co1-xMnxO3-δ (LSCM) with triple H+/O2-/e- conductivity as the air electrode for PCCs. Specifically, the La0.8Sr0.2Co0.8Mn0.2O3-δ (LSCM8282) incorporates 5.8% proton carriers in molar fraction at 400 °C, indicating superior proton conducting ability. Impressively, a high current density of 1580 mA cm−2 for hydrogen production (water electrolysis) is achieved at 1.3 V and 650 °C, surpassing most low- and high-temperature devices reported so far. Meanwhile, such a PCC can also be operated under a reversible fuel cell mode, with a peak power density of 521 mW cm−2 at 650 °C. By correlating the electrochemical performances with the hydrated proton concentration of single-phase triple conducting air electrodes in this work and our previous work, a principle for rational design of high-performance PCCs is proposed.