Fascinating bifunctional electrocatalytic activity via a mesoporous structured FeMnO3@ZrO2 matrix as an efficient cathode for Li-O2 batteries

Nonaqueous Li-O2 batteries have remarkable potential for use in future-generation sustainable green energy storage systems. Perovskites of the type ABO3 provide bifunctional electrocatalytic activity superior to that of dual mixed-metal oxides due to the presence of crystallographic defects and oxygen vacancies, arising from the multivalency of the A and B cations. In this study, we used a facile hydrothermal method with an ammonia solution to modify coralline-like ZrO2 with Fe0.5Mn0.5O3 (FeMnO3) and graphene nanosheets (GNSs). The porous structure of the resulting ZrO2@FeMnO3/GNS system featured a high surface area and large volume, thereby exposing a great number of active sites. X-ray photoelectron spectroscopy revealed that the surface of the as-synthesized FeMnO3@ZrO2/GNS cathode material was rich with oxygen vacancies (i.e., a huge quantity of defects). This coralline-like bifunctional electrocatalyst possessed effective redox capability between Li2O2 and O2 as a result of its excellent catalytic activity in the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). We examined the charge/discharge behavior of corresponding electrodes (EL-cell type for Li-O2 battery) in the voltage range of 2.0-4.5 V (vs Li/Li+). The synergistic effects of the high catalytic ability and coralline-like microstructure of our ZrO2@FeMnO3/GNS catalyst for Li-O2 batteries resulted in its superior rate capability and excellent long-term cyclability, sustaining 100 cycles at 100 mA g-1 with a limited capacity of 1000 mAh g-1. The cell overpotential was ∼0.14 V when adding LiI as a redox mediator, resulting in a more practical Li-O2 battery with the ZrO2@FeMnO3/GNS catalyst. Therefore, ZrO2@FeMnO3/GNS catalysts having distinctive coralline-like structures can display outstanding bifunctional catalytic activity and electrical conductivity, suggesting great potential for enhanced Li-O2 battery applications

Preparation of g-C3N4/ZIF-8/PVDF–modified Li anode for all-solid-state Li metal batteries

All-Solid-state lithium metal batteries (ASSLMBs) are promising next-generation energy storage devices. However, the formation of lithium (Li) dendrites in ASSLMBs limits their applications. In this study, we used an inorganic/organic mixture of graphitic carbon nitride (g-C3N4), zinc-based Zeolitic Imidazolate Framework-8 (ZIF-8), and poly(vinylidene difluoride) (PVDF)—g-C3N4/ZIF-8/PVDF (g-CNZP)—to modify the surface of a lithium metal anode (LMA). The 2032-type coin cell was assembled based on a lithium Nafion (LiNf)–coated NCM811 (denoted as LiNf@NCM811) cathode, inorganic/organic mixture modified Li metal anode (LMA) (denoted g-CNZP@Li), and a LiNf-coated Li6.05Ga0.25La3Zr2O11.8F0.2 ([email protected]) filler in bilayer hybrid solid electrolyte (Bi-HSE). The coin cell was charged between 2.8 and 4.2 V at 0.5C exhibited an initial specific discharge capacity of 134.45 mAh g−1 and retained 86.1 % of its capacity after 280 cycles at 30 °C. The average coulombic efficiency of the cell was approximately 99.8 %. Furthermore, the high-voltage (2.8–4.5 V, at a rate of 0.2C) result also delivered an initial specific discharge capacity of 194.3 mAh g−1 and, after 100 cycles, maintained 81.8 % of its initial capacity at room temperature. The presence of the nanosheet/nanoparticle composite coating material on the LMA surface suppressed Li dendrite growth and enhanced the compatibility between the LMA and Bi-HSE membrane. In addition, the in-situ formation of Li3N on the solid electrolyte interface (SEI) layer improved the ionic conductivity and ensured intimate interfacial contact during cycling. Therefore, these novel bi-layered fabrication strategies for obtaining hybrid/composite solid electrolyte membranes and modifying LMA surfaces via 2D g-C3N4 material with ZIF-8 MOFs and PVDF composites appear to have applicability in the preparation of very safe high-voltage cathodes for ASSLMBs