Bioderived Calcite as Electrolyte for Solid Oxide Fuel Cells: A Strategy toward Utilization of Waste Shells

The excessive consumption of synthesized materials and enhanced environmental protection protocols necessitate the exploitation of desirable functionalities to handle our solid waste. Through a simple calcination and composite strategy, this work envisages the first application of biocalcite derived from the waste of crayfish shells as an electrolyte for solid oxide fuel cells (SOFCs), which demonstrates encouraging performances within a low temperature range of 450-550 °C. The single cell device, assembled from calcined waste shells at 600 °C (CWS600), enables a peak power density of 166 mW cm^-2 at 550 °C, and further renders 330 and 256 mW cm^-2 after compositing with perovskite La_0.6Sr_0.4Co_0.8Fe_0.2O_3-δ (LSCF) and layer-structured LiNi_0.8Co_0.15Al_0.05O₂ (LNCA), respectively. Notably, an oxygen-ion blocking fuel cell is used to confirm the proton-conducting property of CWS600 associated electrolytes. The practical potential of the prepared fuel cells is also validated when the cell voltage of the cell is kept constant value over 10 h during a galvanostatic operation using a CWS600-LSCF electrolyte. These interesting findings may increase the likelihood of transforming our solid municipal waste into electrochemical energy devices, and also importantly, provide an underlying approach for discovering novel electrolytes for low-temperature SOFCs.