Design of multifunctional interfaces on ceramic solid electrolytes for high-performance lithium-air batteries

High-energy-density lithium (Li)-air cells have been considered a promising energy-storage system, but the liquid electrolyte-related safety and side-reaction problems seriously hinder their development. To address these above issues, solid-state Li-air batteries have been widely developed. However, many commonly-used solid electrolytes generally face huge interface impedance in Li-air cells and also show poor stability towards ambient air/Li electrodes. Herein, we fabricate a differentiating surface-regulated ceramic-based composite electrolyte (DSCCE) by constructing disparately LiI-containing polymethyl methacrylate (PMMA) coating and Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) layer on both sides of Li1.5Al0.5Ge1.5(PO4)(3) (LAGP). The cathode-friendly LiI/PMMA layer displays excellent stability towards superoxide intermediates and also greatly reduces the decomposition voltage of discharge products in Li-air system. Additionally, the anode-friendly PVDF-HFP coating shows low-resistance properties towards anodes. Moreover, Li dendrite/passivation derived from liquid electrolyte-induced side reactions and air/I-attacking can be obviously suppressed by the uniform and compact composite framework. As a result, the DSCCE-based Li-air batteries possess high capacity/low voltage polarization (11,836 mA h g(-1)/1.45 V under 500 mA g(-1)), good rate performance (capacity ratio under 1000 mA g(-1)/250 mA g(-1) is 68.2%) and long-term stable cell operation (similar to 300 cycles at 750 mA g(-1) with 750 mAh g(-1)) in ambient air.