Advanced composite electrolyte membranes for enhanced ionic conduction in ceramic fuel cells

Solid oxide fuel cells (SOFCs) are renowned for their high efficiency in converting chemical energy into electrical energy. However, their widespread adoption is limited by the high operating temperatures (typically 800–1000 °C) required by conventional electrolytes. To overcome this challenge and improve the performance of electrochemical conversion devices, it is crucial to develop electrolytes with high ionic conductivity, power density, open-circuit voltage (OCV), and energy efficiency. A promising approach involves the use of wide-bandgap semiconductor perovskites known for their excellent power efficiency. Among these materials, SrTiO3 (STO) has attracted considerable attention due to its potential for delivering high-performance fuel cells at reduced temperatures. Building on the potential of SrTiO3, we designed a semiconductor heterostructure to enhance its performance further. This study focuses on a heterostructure composed of SrCo0.2TiO3 (SCT) and ZnO, which acts as an electrolyte and significantly improves ionic conduction. Our results demonstrate that the SCT-ZnO heterostructure, when used as an electrolyte in a ceramic fuel cell (CFC) device, achieved an impressive power density of 882 mW cm−2 and ionic conductivity of 0.22 S cm−1 at a reduced operating temperature of 525 °C. The enhanced performance is attributed to the heterostructure design, the presence of enriched oxygen vacancies at the interface, and the built-in electric field (BIEF) at the SCT-ZnO interface, which enhances ionic conduction by creating a space charge region driven by differential Fermi levels between the materials. This heterostructure-based approach offers a promising path for developing next-generation ceramic fuel cells by combining wide-bandgap semiconductors with superior ionic conductivity for enhanced fuel cell performance. By enabling efficient energy conversion from renewable energy fuel such as hydrogen gas, this technology directly supports the advancement of renewable energy solutions, contributing to reduced greenhouse gas emissions and a sustainable energy future.