Organic-inorganic interlayer enabling the stability of PVDF-HFP modified Li metal for lithium-oxygen batteries

PVDF-HFP layer has been used in lithium (Li) metal-based batteries for its high Li-ion conductivity, excellent mechanical strength and water-proof property. Moreover, the layer reacts with Li metal and improves the performance of solid electrolyte interphase (SEI) by introducing the additional component of LiF. Herein, we further allow an organic molecular (11-mercaptoundecanoic acid, MUA) to involve in the reaction between the PVDF-HFP layer and Li metal, which results in an organic–inorganic SEI interlayer consisting of Li2S, LiF, lithium alkyl carbonate (RCOOLi), and MUA-Li etc. This interlayer shows the high Li+ transfer number (0.62) and Young’s modulus (6.17 GPa), which also serves to increase the adhesion between PVDF-HFP and Li metal. By using the organic–inorganic interlayer enhanced PVDF-HFP coated Li metal, the Li/Li symmetric cells can run for at least 2190 h steadily, and the Li-oxygen batteries can operate for 214 cycles, demonstrating the improved protection and ionic conductivity of Li metal anodes.