A Novel High‐Entropy Perovskite Electrolyte with Improved Proton Conductivity and Stability for Reversible Protonic Ceramic Electrochemical Cells

Abstract

Reversible protonic ceramic electrochemical cells (R‐PCECs) are emerging as highly efficient energy conversion devices, operating below 650 °C. The primary challenge in advancing R‐PCECs lies in developing efficient and stable proton‐conducting electrolytes capable of withstanding the chemical instability caused by common contaminants like CO2 and H2O. Herein, a novel high‐entropy perovskite oxide (HEPO) material is introduced, incorporating six equimolar B‐site cations (BaHf1/6Sn1/6Zr1/6Ce1/6Y1/6Yb1/6O3‐δ, BHSZCYYb). The total conductivity of BHSZCYYb outperforms that of the examined HEPO electrolytes and other reported HEPO variants. Additionally, superior chemical stability of BHSZCYYb is observed when exposed to CO2. Utilizing the microwave‐assisted sintering method, an R‐PCEC with BHSZCYYb electrolyte is successfully fabricated. This cell exhibits a maximum power density of 1.151 W cm−2 (650 °C) in fuel cell mode and a current density of 2.326 A cm−2 at 1.3 V (650 °C) in electrolysis cell mode. These results represent the highest‐reported values for R‐PCECs employing HEPO electrolytes to date and provide valuable insights into the development and advancement of HEPOs, holding great promise for achieving high‐performance R‐PCECs.

Working Principles of High-Entropy Electrolytes in Rechargeable Batteries

“…However, the research on practical solid-state Li batteries with high battery-level energy density and high safety is at an early stage. It is still a challenge to design SSEs with low cost, high ionic conductivity, and excellent interfacial compatibility with positive and negative electrodes. , Therefore, more attention needs to be paid to the design of novel solid-state HEEs to regulate the structural and interfacial chemistry in SSEs. The design of safe and efficient semisolid electrolytes based on high entropy may be a prospective research direction.…”