乙基碘化胺驱动锂氧气电池溶剂相介导及固体电解质界面原位构筑

Li-O₂ batteries have sparked significant interest and research due to their impressive theoretical energy density (3500 Wh kg⁻¹). Despite this, the slow kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as well as the insulating nature of the discharge products, remain critical limiting factors that impact the cycling stability and rate performance of Li-O₂ batteries. Various solid-state electrocatalysts, such as transition metal oxides, non-precious metals, and nitrides, have been proven to decrease the overpotential of Li-O₂ batteries during the charging process. However, their catalytic effectiveness is restricted by inadequate contact at the interface with Li₂O₂ and the effects of surface coverage. In contrast, soluble redox mediators (RMs) demonstrate exceptional solid-liquid interface contact and efficient charge transport capabilities, allowing them to effectively regulate the formation and decomposition of discharge products. This accelerates the reaction kinetics of the oxygen cathode, reduces battery overpotential, and ultimately enhances both the cycle life and rate performance of the battery. Nevertheless, the RM_ox that forms at the cathode can diffuse through the separator to the anode, causing the corrosion of lithium metal and reducing the RM_ox. This will lead to an increase in polarization potential and a decline in cycling performance. To address these issues, we have developed a novel “self-defense” additive material tailored for Li-O₂ batteries to mitigate side reactions induced by RMs. The EA⁺ cations, known for their electrophilic properties, tend to capture negatively charged O₂⁻ during discharging process, facilitating the solution discharge pathway and boosting full discharge capacity. In the charging process, the I⁻ in the additive assists in decomposing discharge products, reducing charge overpotential, and enhancing battery cycling stability and rate performance. Moreover, EA⁺ can attach to the Li anode surface, contributing to the formation of a mixed organic-inorganic solid electrolyte interface (SEI) layer that shields the Li metal from DMSO and iodide attacks, effectively preventing Li corrosion and dendrite growth. Analysis through scanning electron microscope, atomic force microscope, and X-ray photoelectron spectroscopy techniques of the anode surface indicates smoother and more uniform lithium deposition, along with a more stable SEI film composition.