High ionic conductivity PEO-based electrolyte with 3D framework for Dendrite-free solid-state lithium metal batteries at ambient temperature

Abstract Solid-state lithium metal batteries are one of the best candidates for the next generation of energy storage devices. However, their applications are greatly limited by low ionic conductivity at ambient temperature and poor interfacial compatibility of solid-state electrolytes. Herein, a novel composite solid-state electrolyte consisted of polyethylene oxide (PEO), aramid nanofibers (ANFs) and Li7La3Zr2O12 (LLZO) was designed and prepared. The ANFs and PEO constructed a three-dimensional flexible framework by electrostatic attraction, and LLZO particles as Li+-conducting fillers were introduced into the polymer backbone. As a result, compared to the pure PEO host, the crystallinity of prepared electrolyte was remarkably decreased, and the ionic conductivity was increased to 1.36 mS cm-1 at 30 °C. LiFePO4/Li cells with the electrolyte delivered a high specific capacity of 152 mAh g-1 and the capacity retention was over 88 % after 400 cycles, and the LiNi0.6Co0.2Mn0.2O2/Li cell can stably operate 200 cycles at 0.5C under 30 °C. During cycling, a stable solid electrolyte interphase (SEI) was formed on the surface of lithium anode, inhibiting the formation of lithium dendrite and dead lithium, and improving the cyclic stability of the battery. Furthermore, the electrolyte exhibited satisfactory mechanical properties, high thermal stability, and good interfacial compatibility and stability with the lithium metal anode. This work could provide a reference for the development and practical application of solid-state lithium metal batteries at ambient temperature.