Cellulose mesh supported ultrathin ceramic-based composite electrolyte for high-performance Li metal batteries

Abstract

Oxide electrolytes show great potential in solid-state batteries due to their good stability and high ionic conductivity. However, some fatal shortcomings such as complex manufacture, large thickness, inferior flexibility and poor contact with electrodes caused by intrinsic rigidity and brittleness of oxides hinder their large-scale commercial application. Herein, an ultrathin ceramic (LAGP) membrane supported by light-weight cellulose mesh (LAC) is fabricated by a facile solution-casting method, in which a few PVDF serves as binder. Then gel electrolyte containing FEC is introduced on both sides of LAC by in-situ polymerization method to resolve the interfacial issue including poor contact and incompatibility between electrodes and LAC. The ultrathin LAC ceramic membrane presents a thickness of about 21 μm and exhibits superior flexibility, and the obtained gel electrolyte modified ceramic-based composite electrolyte (LACF) displays ultrahigh ionic conductance (86.05 mS), wide electrochemical window (4.7 V) and high Li+ transference number (0.54) at 25 °C. More importantly, the LACF composite electrolyte shows good stability to Li anode due to the LAC membrane with high proportion of mechanically-robust ceramic particles and FEC-containing gel electrolyte interlayer, which enables stable and uniform Li stripping/plating in Li/LACF/Li cell for 300 h at 0.1 mA cm−2. As a consequence, the LFP/LACF/Li full cell demonstrates excellent cyclic stability as the discharge capacity just shows an extremely minor decrease after 180 cycles at 0.5 C. Therefore, this work provides a novel insight for preparing flexible ceramic-based composite electrolyte which enables high-performance and safe Li metal batteries.