Toward system-level energy density enhancement in solid oxide cells through 3D structural design

Abstract

As the demand for clean energy systems rises with increasing electricity consumption, solid oxide cells (SOCs) emerge as one of the major energy conversion technologies owing to their high efficiency, fuel flexibility, and compatibility with hybrid systems. Such features position SOCs as promising energy conversion systems for stationary power generation and heavy-duty transportation. However, their broader deployment, particularly in aircraft, is constrained by limited system-level energy conversion density, since excessive mass and volume reduce propulsion efficiency and increase costs, highlighting the need for further improvements in overall system efficiency. While most prior efforts have focused on materials development to improve electrochemical performance, geometric optimization provides an alternative pathway to enhance volumetric and gravimetric power density without relying on new or high-cost material systems. Here, we present a structure-driven perspective that links three-dimensional (3D) SOC geometries to stack-level energy conversion efficiency, mass and volume efficiency, and overall system economics. By analyzing reported 3D geometries for SOCs, we highlight how increased surface-to-volume ratios and reduced stack-component mass fractions can substantially improve system-level energy conversion density while lowering cost metrics. This work shifts the focus of SOC advancement from a material-centric approach toward integrated structure–manufacturing–system design, positioning 3D structural strategies as scalable pathways toward high-energy-density, lightweight SOC systems.