Robust fluorite-structured high-entropy oxides with integrated multi-active site construction for Li-CO2 batteries catalytic cathodes

Abstract

As emerging high-energy storage devices, lithium-carbon dioxide (Li-CO2) batteries facilitate carbon neutrality and address the current limitations of lithium-ion batteries in terms of energy density. Stable and highly active catalytic cathodes constitute a pivotal factor in driving the commercialization of Li-CO2 batteries regard to reactant activation and decomposition of discharge products timely. Herein, a ceria-based high-entropy oxides (HEOs), denoted as CeFeCoNiMnOx, is synthesized by exploiting the exceptional heterogeneity-tolerant properties of fluorite-structured cerium oxide (CeO2). Leveraging the robust structural and chemical stability of the CeO2 framework, the encapsulated polymetallic active sites within the oxide are effectively integrated, thereby enhancing the electrochemical performance of the cathode. The resultant Li-CO2 battery demonstrates remarkable discharge voltage at 2.98 V, substantial discharge capacity of 11128 mAh g-1 as well as exceptional cycling stability of 171 cycles based on the HEOs at current rate of 100 mA g-1. Benefiting from the effective decomposition of discharge products by the synergistic action of multiple active sites, the cell exhibits a leading low overpotential at 0.91 V. The innovative design approach of utilizing fluorite-structured CeO2 as a substrate for the integration of multiple active sites and the subsequent construction of HEOs broadens the spectrum of catalytic cathodes for Li-CO2 batteries.