Towards a scalable recycling process for ceramics in fuel-electrode-supported solid oxide cells

Abstract

The solid oxide cell (SOC) technology relies on high-performance ceramics containing strategically valuable and critical raw materials. This study focuses on the processing of spent cell materials from fuel-electrode-supported SOCs, demonstrating the feasibility of utilizing a significant portion of the ceramic cell in a closed-loop system. More than 85% of the cell's initial mass was directly incorporated into substrate manufacturing. The air-side perovskites were initially separated using hydrochloric acid treatment, followed by mechanical reprocessing of the remaining half cells. The performance of the resulting full cells containing 50 mass% recycled material in the substrate was evaluated, achieving a current density of up to 1.14 A cm⁻² at 0.7 V and 750 °C in fuel cell mode, which is comparable to that of non-recycled counterparts. Preliminary experiments for the recovery of leached metal ions from the air electrode were conducted using direct oxalate precipitation while examining pH dependence. Direct oxalate precipitation proved particularly effective in the low pH range for the recovery of a lanthanum oxalate precursor with a purity exceeding 98%. The results highlight the potential for simple and sustainable practices in SOC technology.